The word 'too-familiar' is a modern English compound formed by combining the intensifying adverb 'too' with the adjective 'familiar'. 'Too' originates from Old English 'tō', which carried the sense of 'beyond a limit'. 'Familiar' traces back to Latin 'familiaris', denoting the intimate, private sphere of the household ('familia'). The compound's logic is transparent: it describes a state of knowingness or intimacy that has transgressed its proper boundary, moving from the acceptable realm of the known into the excessive and often socially inappropriate. Thus, it captures the nuanced social judgment where comfort becomes overreach.

Structure: too (excessively) + familiar (well-known) - too: From Old English 'tō', an adverb meaning 'in addition, also, excessively'. In this compound, it functions as an intensifying prefix meaning 'excessively'. - familiar: From Latin 'familiaris' (of a household, domestic), from 'familia' (family). It functions as an adjective meaning 'well-known, intimate, or common'.