The compound "two-finger" is a transparent Modern English formation, directly combining the numeral and the noun. The word "two" descends from the Proto-Indo-European root dwóh₁, which is the source for the fundamental numeral across many Indo-European languages, including Latin 'duo' and Greek 'δύο' (dyo). "Finger" originates from Proto-Germanic fingraz, whose own earlier origin is uncertain but may be connected to a root meaning 'five', reflecting the hand's digits. The compound's logic is purely descriptive, specifying a quantity of fingers involved in a particular action or gesture, with its specific conventional meanings (like the salute or typing style) arising through 20th-century usage.

Structure: two (number) + finger (body part) - two: From Old English 'twā', of Germanic origin; related to Dutch 'twee' and German 'zwei', from an Indo-European root shared by Latin 'duo' and Greek 'duo'. Functions as a numerical quantifier. - finger: From Old English 'finger', of Germanic origin; related to Dutch 'vinger' and German 'Finger'. Functions as a noun denoting a specific body part.