the word 'warmth' is a native english formation, originating from the old english adjective 'wearm', which meant having a moderate or pleasant heat. this adjective has deep germanic roots, traceable to the proto-germanic 'warmaz', and further back to the proto-indo-european root 'gʷʰer-', meaning 'warm' or 'hot'. to this core adjective, the old english abstract noun suffix '-þu' was added, which evolved into the modern '-th', a common suffix for forming nouns denoting a state or condition (as in 'strength', 'length'). thus, 'warmth' literally means 'the state or quality of being warm', a meaning which seamlessly extended from physical heat to encompass metaphorical qualities of kindness and affection.

Structure: warm (having heat) + th (state or quality) warm (from old english 'wearm', of germanic origin, meaning having a moderate degree of heat). th (from old english '-þu', '-þo', a noun-forming suffix denoting a state or quality).