A hypocorism (from Greek ὑποκορίζεσθαι hypokorizesthai, "to use child-talk") is a shorter or diminutive form of a word or given name, for example, when used in more intimate situations as a nickname or term of endearment.

Hypocorisms are often generated as:

As evident from the above-mentioned examples, hypocorisms frequently demonstrate (indirectly) a phonological linguistic universal (or tendency) for high-pitched sounds to be used for smaller creatures and objects (here as more "cute" or less imposing names). Higher-pitched sounds are associated with smaller creatures because smaller creatures can only make such high frequency sounds given their smaller larynx sizes.

The word "hypocorism" is the noun form in English; "hypocoristic" is the adjective form. Some other languages^[which?] prefer to use the original Greek word "hypocoristicon" as a noun.^{[citation needed]} The noun "hypocoristicon" seems to be rarely used in English.^{[citation needed]}

English also forms nicknames in a variety of manners.

In the English language, black sheep is an idiom used to describe an odd or disreputable member of a group, especially within a family. The term has typically been given negative implications, implying waywardness. It derived from the atypical and unwanted presence of other black individuals in flocks of white sheep.

In psychology, the black sheep effect refers to the tendency of group members to judge likeable ingroup members more positively and deviant ingroup member more negatively than comparable outgroup members.

The term originated from the occasional black sheep which are born into a flock of white sheep due to a genetic process of recessive traits. Black wool was considered commercially undesirable because it could not be dyed. In 18th and 19th century England, the black color of the sheep was seen as the mark of the devil. In modern usage, the expression has lost some of its negative connotations, though the term is usually given to the member of a group who has certain characteristics or lack thereof deemed undesirable by that group.