the word 'toothache' is a transparent compound formed from two old english elements. 'tooth' descends from the proto-germanic 'tanþs', which itself originates from the proto-indo-european root 'h₃dónts', meaning tooth. 'ache' as a noun for pain comes from old english 'æce', related to the verb 'acan' (to hurt), with possible connections to a proto-germanic root for grief. the compound logically and literally denotes a 'tooth-pain,' a direct and enduring description of the condition that has remained semantically stable from its old english formation into modern english.

Structure: tooth (body part) + ache (pain) tooth (from old english 'tōþ', of germanic origin; a body part) + ache (from old english 'æce', a noun meaning pain, later influenced by the verb 'acan' meaning to hurt)