'nonwavy' is a formed compound using the prefix 'non-' (from Latin/Old French 'non', meaning 'not') combined with 'wavy' (from 'wave' + suffix '-y'), where 'wave' denotes a waving or undulating form.

'non-' has long been used in English as a productive negating prefix; 'wave' comes from Old English (cf. 'wafian'/'wæg') meaning to move back and forth, which became Middle English 'wave' and then modern English 'wave'; 'wavy' developed from 'wave' + adjectival suffix '-y', and 'nonwavy' is a more recent, transparent negated adjective formed from these parts.

The components originally meant 'not' (non-) and 'having waves' (wavy); combined, the compound now straightforwardly means 'not having waves' (i.e., smooth or without undulation).