lit-up

The compound adjective 'lit-up' is a relatively modern formation, emerging from the phrasal verb 'to light up'. The core verb 'light' originates from the Old English 'līhtan', meaning 'to shine, illuminate, or kindle', which itself has Proto-Germanic origins. The particle 'up' is of ancient Germanic lineage, commonly used to indicate completion or intensification. When combined, the literal sense of 'illuminated from within' evolved naturally into a metaphorical description for a face or place glowing with light, energy, or emotion. This transition from a physical description to an emotional one exemplifies a common semantic shift where visual brightness is equated with positive internal states.

Structure: lit (past participle of 'light') + up (adverbial particle) - lit: From Old English 'līhtan', meaning 'to illuminate'. In this structure, it is the past participle form of the verb 'light', functioning as an adjective. - up: From Old English 'ūp', an adverb and preposition meaning 'to a higher place or position'. Here it functions as an adverbial particle, intensifying or completing the meaning of the participle.