A cutlass is a short, broad sabre

Sabre

The sabre or saber is a kind of backsword that usually has a curved, single-edged blade and a rather large hand guard, covering the knuckles of the hand as well as the thumb and forefinger...

 or slashing sword

Sword

A sword is a bladed weapon used primarily for cutting or thrusting. The precise definition of the term varies with the historical epoch or the geographical region under consideration...

, with a straight or slightly curved blade

Blade

A blade is that portion of a tool, weapon, or machine with a cutting edge and/or a pointed tip that is designed to cut and/or puncture, stab, slash, chop, slice, thrust, or scrape animate or inanimate surfaces or materials...

 sharpened on the cutting edge, and a hilt

Hilt

The hilt of a sword is its handle, consisting of a guard,grip and pommel. The guard may contain a crossguard or quillons. A ricasso may also be present, but this is rarely the case...

 often featuring a solid cupped or basket

Basket-hilted sword

The basket-hilted sword is the name of a group of early modern sword types characterized by a basket-shaped guard that protects the hand. The basket hilt is a development of the quillons added to swords' crossguards since the Late Middle Ages...

 shaped guard. It was a common naval weapon.
The word cutlass developed from a 17th-century English variation of coutelas, a 16th-century French word for a machete

Machete

The machete is a large cleaver-like cutting tool. The blade is typically long and usually under thick. In the English language, an equivalent term is matchet, though it is less commonly known...

-like blade (modern French for "knife", in general, is "couteau" The word is often spelt "cuttoe" in 17th and 18th century English).