pet name
n. countablen. a special, affectionate name that you use for a close friend, family member, or romantic partner instead of their real name. Common examples include 'honey', 'buddy', or 'sweetie'.
n. an informal, affectionate name used by intimates in place of a given name. Often functions as a hypocorism between romantic partners or family members.
He calls his girlfriend 'honey' as a pet name.
The couple had several silly pet names for each other that they only used when they were alone at home.
Linguistic studies of endearment suggest that pet names often employ diminutive suffixes to signal emotional closeness and social intimacy between interlocutors.
Commonly used with the verb 'to have' or 'to use'; often paired with 'for' (e.g., 'a pet name for her son').