it can mean fluent.Sentance: Denise Jonas is proficient in sign language.
3 syllables (pro-fic-ient) hope this helps:)
'Proficient' has two senses or meanings: 1: of or relating to technique or proficiency in a practical skill; 2: having or showing knowledge and skill and aptitude
Able, skilled, adept, capable, effective, and efficient.
You could say "nonproficient"; "unproficient" isn't really a "word" (you can say it, but it's unusual).