In cladistics, a character or trait shared by two or more taxonomic groups and derived from a remote or much earlier common ancestral form.

In cladistics, a character or trait shared by two or more taxonomic groups and derived from a common ancestral form, whose ancestor in turn did not possess that trait.

Spawning behaviour in which all individuals of a species spawn in unison, normally as a result of some environmental trigger or cue.

In zoological nomenclature, any of two or more names of the same taxonomic rank used to denote the same taxon. Names referred to as synonyms are not usually valid in the current sense.

Having the same or similar meaning, significance or implication; being a synonym of something.

The quality or state of being synonymous; a list or record of all synonyms that have been applied to a species or group

Brief outline or description of a taxon.

Occupying the same habitat within a specified geographical area, and sometimes competing for resources as a result.

Any specimen within a type series if no holotype or lectotype has been designated, the syntypes collectively representing the name-bearing type.

Branch of biology concerned with classification and nomenclature of organisms, and the relationships between them; taxonomy.