'booer' originates from English, specifically the word 'boo', which is imitative in origin (an example of onomatopoeia) and represents the sound 'boo' used to express contempt or disapproval; the agentive suffix '-er' is added to form 'booer'.

'boo' (mid 16th century) is an imitative exclamation; the agentive suffix '-er' (from Germanic, Old English '-ere') was attached to form nouns meaning 'one who does X', producing 'booer' in modern English.

Initially 'boo' referred to the exclamation imitating the sound 'boo'; over time it came to mean an expression of contempt or disapproval, and 'booer' developed to mean 'one who expresses such disapproval.'