"act of touching, feeling by the sense of touch," late 15c. (Caxton), from French palpation, from Latin palpationem (nominative palpatio) "a stroking; flattering, flattery," noun of action from past-participle stem of palpare "to touch" (see palpable). Used in English in literal sense.
late 14c., "that can be felt, perceptible by the touch," from Late Latin palpabilis "that may be touched or felt," from Latin palpare "touch gently, stroke," a word de Vaan finds to be of no known etymology (rejecting the connection in Watkins, etc., to a reduplication of the PIE root *pal-, as in feel (v.), on phonetic grounds). Some sources suggest it is onomatopoeic. The figurative sense of "easily perceived, evident, clear, obvious" also is from late 14c., on the notion of "seeming as if it might be touched." Related: Palpably; palpability.