any number of entities (members) considered as a unit | a canal for a current of water |
a set that is closed, associative, has an identity element and every element has an inverse | a contest of speed |
(chemistry) two or more atoms bound together as a single unit and forming part of a molecule | any competition |
| people who are believed to belong to the same genetic stock |
| (biology) a taxonomic group that is a division of a species; usually arises as a consequence of geographical isolation within a species |
| the flow of air that is driven backwards by an aircraft propeller |