Noun

1. The act of applying; application.
2. An implement, an instrument or apparatus designed (or at least used) as a means to a specific end (often specified).
3. Specifically: A non-manual apparatus or device, powered electrically or by another small motor, used in homes to perform domestic functions (household appliance) and/or in offices.
4. An attachment, some equipment (or - piece) to adapt another tool or machine to such specific purpose
5. (obsolete) compliance