'oak-flavored' is a Modern English compound formed from 'oak' + 'flavored'. 'Oak' originates from Old English 'āc' (from Proto-Germanic '*akmaz') meaning 'oak (tree)'. 'Flavor' entered English via Old French 'flavour' and Middle English, ultimately influenced by Latin elements (e.g. 'flāvus' 'yellow' in related formations); 'flavored' is the past-participle/adjectival form meaning 'having flavor'.

'oak' changed from Old English 'āc' through Middle English forms (e.g. 'oke', 'ok') to the Modern English 'oak'. 'Flavor' entered Middle English from Old French 'flavour' and developed into Modern English 'flavor'/'flavour'; the adjectival form 'flavored' has been used in compounds such as 'oak-flavored' in modern usage to denote taste imparted by oak.

Initially, 'oak' referred simply to the tree and 'flavor' to taste or smell; over time the compound came to mean specifically 'having the taste or aroma imparted by oak (often from oak barrel aging)'.