tucks / tux are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
tucks: (noun) eatables (especially sweets). (noun) (sports) a bodily position adopted in some sports (such as diving or skiing) in which the knees are bent and the thighs are drawn close to the chest. (noun) a narrow flattened pleat or fold that is stitched in place. (verb) fit snugly into. (verb) make a tuck or several folds in.
tux: NA
tucks: t·AH·k·s
tux: t·AH·k·s
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)