səˈplēshən noun
( -s )
Etymology: Medieval Latin suppletion-, suppletio act of completing, supplementing, from Latin suppletus (past participle of supplēre to fill up, complete, supply) + -ion-, -io -ion — more at supply
: the occurrence of phonemically unrelated allomorphs of the same morpheme whether that morpheme is a base (as go, past tense went; bad, comparative worse ) or an affix (as plural ending -es in boxes, -en in oxen )