The Collaborative International Dictionary
Irreptitious
Irreptitious \Ir`rep*ti"tious\, a. [L. irrepere, irreptum, to
creep in; pref. ir- in + repere to creep.]
Surreptitious; spurious. [Obs.]
--Dr. Castell (1673).
Wiktionary
irreptitious
a. (context obsolete English) surreptitious; spurious