In grammar, a form that is of a different origin from what you would expect to be a related form. For example, in English the past tense of go is not *"goed" (though archaic words yode and yede do exist) but went, originally from the verb wend.

In Latin fero 'I carry' would be expected to have perfect something like *ferui and supine *fertum, but in fact it uses tuli and latum. (These two themselves look unlike but latum comes from earlier tlatum, the same root as in Greek Atlas, the bearer.)

Sup"ple*tive (?), Sup"ple*to*ry (?), a. [Cf. F. suppl'etif, LL. suppletivus, from L. supplere, suppletum, to fill up. See Supply.]

Supplying deficiencies; supplementary; as, a suppletory oath.

 

© Webster 1913.