Hypocorism

A hypocorism ( or  ; from Ancient Greek:  (hypokorisma), sometimes also hypocoristic), or pet name is a name used to show affection for a person. It may be a diminutive form of a person's name, such as Izzy for Isabel or Bob for Robert, or it may be unrelated, such as best friends calling each other by an affectionate name unrelated to given names like "twin star", a husband and wife calling each other "baby", or when a pet named "Tabitha" is called something unrelated to its root name such as "brownie" or "baba", or related to baby talk pronunciations for longer words like Grandma becoming "gams".

Etymologically, the term hypocorism is from Ancient Greek (hypokorisma), from  (hypokorizesthai), meaning 'to call by endearing names'. The prefix hypo refers in this case to creating a diminutive, something that is smaller in a tender or affectionate sense; the root korizesthai originates in the Greek for 'to caress' or 'to treat with tokens of affection', and is related to the Greek word (kóros) 'boy; youth' and  (kórē), 'girl; young woman'.

In linguistics, the term can be used more specifically to refer to the morphological process by which the standard form of the word is transformed into a form denoting affection, or to words resulting from this process. In English, a word is often clipped down to a closed monosyllable and then suffixed with -y/-ie (phonologically ). Sometimes the suffix -o is included as well as other forms  or templates.

Hypocoristics are often affective in meaning and are particularly common in Australian English, but can be used for various purposes in different semantic fields, including personal names, place names, and nouns. Hypocorisms are usually considered distinct from diminutives, but they can also overlap.