The term 'weigh-in' is a modern English compound noun formed from the verb 'weigh' and the particle 'in'. The verb 'weigh' descends from the Old English 'wegan', meaning to carry or move, which itself traces back to the Proto-Indo-European root weǵh-, meaning to go, transport, or draw. This root connects the concept of moving a load to the process of measuring its heaviness. The particle 'in' specifies the action as occurring within a formal or official setting, such as before an event. The compound thus logically denotes the formal process of measuring and recording weight, a meaning that extended metaphorically to the formal recording of opinions or reactions.

Structure: weigh (to measure weight) + in (particle/adverb) weigh: From Old English 'wegan' (to carry, move, weigh). Germanic origin. Functions as the core verb meaning to measure weight. in: From Old English 'in' (in, into, within). Germanic origin. Functions as an adverbial particle indicating the context or process of the action.