'baby' originates from Middle English, related to 'babe' and imitative infantile speech; the modern use as a verb ('to baby') developed from the noun 'baby' meaning 'infant'.

'baby' developed from Middle English 'babi'/'babe' (imitative of infant sounds) and later extended into a verb form 'to baby' meaning 'to treat like a baby'; the past form 'babied' is formed by regular -ed inflection.

Initially, it referred to the noun 'infant' (a very young child). Over time, it also came to mean 'treat like an infant' (verb) and expanded metaphorically to mean 'handle with extreme care'.