Etymology: Origin uncertain. Probably the same word as either English regional (Cornwall) gook fool, simpleton (late 19th cent.; probably shortened < gookoo , south-western variant of cuckoo n. (compare sense 3 at that entry)) or Scots gook, in the same sense, variant of gowk n. (compare sense 2 at that entry; however, this variant is only rarely attested after the 17th cent.).Compare:a1625 P. Hume Flyting with Montgomerie (Harl.) in G. Stevenson Poems A. Montgomerie (1910) 133 Gooke, [a1585 Tullibardine gok, 1621 Hart gowk], wyte me not to garre the grete.1637 S. Rutherford Let. 7 Sept. in Joshua Redivivus (1664) xxxix. 92 It goeth now under the name of wisdom, for men to cast their cloak over Christ and their profession, as if Christ were stolen goods & durst not be avouched, though this be reputed a piece of policy; yet God esteemeth such men to be but State-fools and Court-gooks.1886 A. Reid Poems, Lyrics & Sonnets 165 'Tis but a poet that can quaff Nectar of the gods—but no a calf—I mean a rhymster—silly gook, Wha'd be the better o' a sook!a1895 T. C. Peter MS Coll. Cornish Words in Eng. Dial. Dict. (1900) II. 695/2 Gook, [a fool, simpleton, blockhead]. Perhaps compare also goo-goo int.

Etymology: Probably shortened < goo-goo n.¹ (compare β. forms at that entry), perhaps with alteration after gook n.¹ (compare sense 2 at that entry).Like its probable etymon goo-goo n.¹ apparently originally denoting a Filipino (as is borne out by the bulk of the early evidence). Probably formed during the early years of the U.S. occupation of the Philippines (1898–1946), and later carried by U.S. armed forces to other countries under U.S. occupation, such as Nicaragua (1912–33) and Haiti (1915–34), in transferred use as a derogatory term for the indigenous inhabitants; widely popularized after the U.S. occupation of south Korea in 1945. (The phonetic similarity with Korean -guk, suffix forming names of countries, e.g. miguk America, hanguk, han'guk Korea, etc., which is often cited as the etymon of this word, is purely coincidental.)