In mathematics and computer science

• Calculus
  Calculus
  Calculus is a branch of mathematics focused on limits, functions, derivatives, integrals, and infinite series. This subject constitutes a major part of modern mathematics education. It has two major branches, differential calculus and integral calculus, which are related by the fundamental theorem...
  
  , also "the calculus", short for "differential calculus" and "integral calculus", which investigate motion and rates of change
• Logical calculus, a formal system
  Formal system
  In formal logic, a formal system consists of a formal language and a set of inference rules, used to derive an expression from one or more other premises that are antecedently supposed or derived . The axioms and rules may be called a deductive apparatus...
  
   that defines a language and rules to derive an expression from premises.
• Precalculus
  Precalculus
  In American mathematics education, precalculus , an advanced form of secondary school algebra, is a foundational mathematical discipline. It is also called Introduction to Analysis. In many schools, precalculus is actually two separate courses: Algebra and Trigonometry...
  
  , a family of mathematical topics that prepare students to begin to study differential and integral calculus
• The calculus of sums and differences (difference operator), also called the finite-difference calculus, a discrete analogue of "the calculus"
• In symbolic logic:
  • the propositional calculus
    Propositional calculus
    In mathematical logic, a propositional calculus or logic is a formal system in which formulas of a formal language may be interpreted as representing propositions. A system of inference rules and axioms allows certain formulas to be derived, called theorems; which may be interpreted as true...
    
    , specifies the rules of inference governing the logic of propositions
  • the predicate calculus, specifies the rules of inference governing the logic of predicates
  • a proof calculus
    Proof calculus
    In mathematical logic, a proof calculus corresponds to a family of formal systems that use a common style of formal inference for its inference rules...
    
    , a framework for expressing systems of logical inference
  • the sequent calculus
    Sequent calculus
    In proof theory and mathematical logic, sequent calculus is a family of formal systems sharing a certain style of inference and certain formal properties. The first sequent calculi, systems LK and LJ, were introduced by Gerhard Gentzen in 1934 as a tool for studying natural deduction in...
    
    , a proof calculus for first-order logic
• Bondi k-calculus
  Bondi k-calculus
  Bondi k-calculus is a method of teaching special relativity originated by Professor Sir Hermann Bondi, and now common in university and college level physics classes.The usefulness of the k-calculus is its simplicity...
  
  , a method used in relativity theory
• Domain relational calculus
  Domain relational calculus
  In computer science, domain relational calculus is a calculus that was introduced by Michel Lacroix and Alain Pirotte as a declarative database query language for the relational data model.In DRC, queries have the form:...
  
  , a calculus for the relational data model
• Epsilon calculus
  Epsilon calculus
  Hilbert's epsilon calculus is an extension of a formal language by the epsilon operator, where the epsilon operator substitutes for quantifiers in that language as a method leading to a proof of consistency for the extended formal language...
  
  , a logical language which replaces quantifiers with the epsilon operator
• Functional calculus
  Functional calculus
  In mathematics, a functional calculus is a theory allowing one to apply mathematical functions to mathematical operators. It is now a branch of the field of functional analysis, connected with spectral theory. In mathematics, a functional calculus is a theory allowing one to apply mathematical...
  
  , a way to apply various types of functions to operators
• Join calculus, a theoretical model for distributed programming
• Lambda calculus
  Lambda calculus
  In mathematical logic and computer science, lambda calculus, also written as λ-calculus, is a formal system for function definition, function application and recursion. The portion of lambda calculus relevant to computation is now called the untyped lambda calculus...
  
  , a formulation of the theory of reflexive functions that has deep connections to computational theory
• Matrix calculus
  Matrix calculus
  In mathematics, matrix calculus is a specialized notation for doing multivariable calculus, especially over spaces of matrices, where it defines the matrix derivative. This notation was to describe systems of differential equations, and taking derivatives of matrix-valued functions with respect...
  
  , a specialized notation for multivariable calculus over spaces of matrices
• Modal μ-calculus, a common temporal logic used by formal verification methods such as model checking
• Non-standard calculus
  Non-standard calculus
  In mathematics, non-standard calculus is the modern application of infinitesimals, in the sense of non-standard analysis, to differential and integral calculus...
  
  , an approach to infinitesimal calculus using Robinson's infinitesimals
• Pi-calculus
  Pi-calculus
  In theoretical computer science, the π-calculus is a process calculus originally developed by Robin Milner, and David Walker as a continuation of work on the process calculus CCS...
  
  , a formulation of the theory of concurrent, communicating processes that was invented by Robin Milner
• Refinement calculus
  Refinement Calculus
  Refinement calculus is a formalized approach to stepwise refinement for program construction. The required behaviour of the final executable program is specified as an abstract and perhaps non-executable "program", which is then refined by a series of correctness-preserving transformations into an...
  
  , a way of refining models of programs into efficient programs
• Rho calculus
  Rho calculus
  The rho-calculus is a formalism intended to combine the higher-order facilities of lambda calculus with the pattern matching of term rewriting.-External links:*...
  
  , introduced as a general means to uniformly integrate rewriting and lambda calculus
• Tuple calculus, a calculus for the relational data model, inspired the SQL language
• Umbral calculus
  Umbral calculus
  In mathematics before the 1970s, the term umbral calculus referred to the surprising similarity between seemingly unrelated polynomial equations and certain shadowy techniques used to 'prove' them. These techniques were introduced by and are sometimes called Blissard's symbolic method...
  
  , the combinatorics of certain operations on polynomials
• The calculus of variations
  Calculus of variations
  Calculus of variations is a field of mathematics that deals with extremizing functionals, as opposed to ordinary calculus which deals with functions. A functional is usually a mapping from a set of functions to the real numbers. Functionals are often formed as definite integrals involving unknown...
  
  , a field of study that deals with extremizing functionals
• Vector calculus (also called vector analysis), comprising specialized notations for multivariable analysis of vectors in an inner-product space

Other meanings

• Calculus (dental)
  Calculus (dental)
  In dentistry, calculus or tartar is a form of hardened dental plaque. It is caused by the continual accumulation of minerals from saliva on plaque on the teeth...
  
  , deposits of calcium phosphate salts on teeth, also known as tartar
• Calculus (medicine)
  Calculus (medicine)
  A calculus is a stone that forms in an organ or duct of the body. Formation of calculi is known as lithiasis...
  
  , a stone formed in the body such as a gall stone or kidney stone
• Battlefield calculus, military
  Military
  A military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...
  
   calculation of all known factors into the decision-making and action-planning process
• Calculus (spider), a genus of family Oonopidae
• Caseolus calculus
  Caseolus calculus
  Caseolus calculus is a species of small air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Hygromiidae, the hairy snails and their allies.-Distribution and conservation status:...
  
  , a genus and species of small land snails
• Professor Calculus
  Professor Calculus
  Professor Cuthbert Calculus is a fictional character in The Adventures of Tintin, the series of classic Belgian comic books written and illustrated by Hergé...
  
  , a fictional character in the comic-strip series The Adventures of Tintin
• Calculus of negligence
  Calculus of negligence
  In the United States, the calculus of negligence, or Hand rule or Hand formula, is a term coined by Judge Learned Hand and describes a process for determining whether a legal duty of care has been breached . The original description of the calculus was in U.S. v...
  
  , a legal standard in U.S. tort law to determine if a duty of care has been breached