Where does “underproficient” come from?

underproficient (English) comes from English proficient, from Latin proficiens, from Latin proficio, from Latin faciō, from Latin -torium, from Latin -tōrius, from Latin -tor, from Proto-Italic -tōr.

underproficient (English): Inadequately proficient

Definitions

  1. Inadequately proficient

Ancestry of “underproficient”, step by step

underproficient traces back through two separate lines of ancestry.

via English proficient

StepLanguageWordMeaning
1EnglishproficientGood at something; skilled; fluent; practiced,...
2Latinproficiensadvancing etc
3LatinproficioI advance, make progress, make headway; I...
4Latinfaciōto do
5Latin-toriumnominative neuter singular of -tōrius; accusative...
6Latin-tōriusory
7Latin-tor-er
8Proto-Italic-tōrForms agent nouns to verb stems
9Proto-Indo-European-tōrDerives agent nouns from verbs, denoting someone...
10Proto-Indo-European-tor-s

via English under

StepLanguageWordMeaning
1EnglishunderIn or at a lower level than; As a subject of;...
2Middle Englishunderunder
3Old Englishunderunder, beneath
4Proto-Germanicunderamong, between; under, beneath; under
5Proto-Indo-Europeanh₁entérbetween
6Proto-Indo-Europeanh₁enin; in, inside
Every word from Proto-Indo-European -tor-sEvery word from Latin -toriumEvery word from Latin -tor