What is the meaning of Cf.?

Preceding an uncertain taxonomic rank, in order to designate a specimen that is hard to identify because of practical difficulties, such as poor preservation.

Compare; compare to; compare with.

See; see also.

abbreviation of cōnfer (“compare”)

cf

abbreviation of cónfer

abbreviation of confróntese

cf.; abbreviation of cymharer, impersonal imperative of cymharu (“to compare”)

Source: wiktionary.org