'non-lignitic' is formed from the negative prefix 'non-' plus the adjective 'lignitic'. 'Lignitic' ultimately relates to Latin 'lignum' meaning 'wood', via the noun 'lignite' (a type of brown coal).

'lignum' (Latin) gave rise to forms meaning 'wood' and then to the noun 'lignite' in modern European languages (via French/Latin), from which the English adjective 'lignitic' was formed; the prefix 'non-' was later attached to create 'non-lignitic'.

Originally related to 'wood' (Latin 'lignum'), the root shifted to name a specific coal type ('lignite'); 'non-lignitic' has the straightforward modern meaning 'not of or relating to lignite'.