it refers to a discrete life form that has properties of mind (i.e. experience and character, cf. sentience)
closed as general reference by tchrist♦, MetaEd, StoneyB, FumbleFingers, RegDwigнt♦ Oct 2 '12 at 9:27
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cf., an abbreviation for the Latin word confer (the imperative singular form of "conferre"), literally meaning "bring together", is used to refer to other material or ideas which may provide similar or different information or arguments. It is mainly used in scholarly contexts, such as in academic (mainly humanities, physics and biology) or legal texts. It is translated, and can be read aloud, as "compare".
Granted, the literal translation from Latin is "compare to". In practice cf means "see also".
As explained by MachineCharmer, it is the abbreviation of Latin 'confer' and it is used in several languages in addition to English.
English being a conservative language has many more of these Latin abbreviations of Latin origin: cf 'i.e.', 'e.g.', 'viz', 'et al', 'ca', 'q.v.', 'a.d.', 'vs', etc... ;-) than other European languages influenced by Latin.
The NOAD reports cf. means "compare with" (used to refer a reader to another written work or another part of the same written work).
It should not be confused with c.f., which means "carried forward" (used to refer to figures transferred to a new page or account).