over-confident (adj.)youdaoicibaDictYouDict
1610s, from over- + confident. Related: Overconfidently.
presume (v.)youdaoicibaDictYouDict
late 14c., "to take upon oneself, to take liberty," also "to take for granted, presuppose," especially overconfidently, from Old French presumer (12c.) and directly from Latin praesumere "anticipate," in Late Latin, "assume" (see presumption). Related: Presumed; presumedly; presuming.
whippersnapperyoudaoicibaDictYouDict
"A young and inexperienced person considered to be presumptuous or overconfident", Late 17th century: perhaps representing whipsnapper, expressing noise and unimportance.