The word 'wigwag' is a playful, reduplicative formation from the early 17th century, created by doubling and slightly altering the verb 'wag'. 'Wag' itself has Middle English and probable Old English origins, related to moving something to and fro. The reduplication 'wig-wag' intensifies the sense of repetitive, oscillating motion, a common pattern in English for creating words that mimic an action (like 'flip-flop' or 'see-saw'). This inherent sense of back-and-forth movement naturally extended from general motion to the specific, coded motion used in flag or light signaling, especially in military contexts, by the mid-19th century.

This is a reduplicative compound, formed by the repetition of the element 'wig', which is an alteration of 'wag'. Its origin is imitative, from Middle English 'wiglen' (to move lightly) and 'waggen' (to sway). Its functional role is to create an emphatic or frequentative verb form through sound symbolism.