The verb 'tap' originates from two intertwined Old English concepts: the noun for a plug or spigot ('tæppa') and the corresponding verb for installing one or drawing liquid through it ('tæppian'). These derive from a common Proto-Germanic source. The core action of striking lightly, as in 'tap on the shoulder', developed later, likely imitative of the short, sharp sound produced. The modern verb 'tapped' is the regular past form, created by adding the '-ed' suffix, a standard grammatical marker in English for indicating past action or state, with the spelling adjusted for phonetic assimilation.

Structure: tap (to strike or draw from) + p (assimilation) + ed (past tense suffix) tap: From Old English 'tæppa' (a tap or spigot) and 'tæppian' (to furnish with a tap, to draw liquid). It is of Proto-Germanic origin and functions as the core verb root. p: A graphic element resulting from the assimilation of the root-final consonant before the suffix. ed: From Old English '-ode', '-ade', '-ed', a suffix used to form the past tense and past participle of weak verbs.