Here are a few English words which aren't used often but have great meanings IMO
Absquatulate.
To up and leave someone all of a sudden.
Blatherskite
someone who doesn't shut up talking nonsense
Doryphore
some one who constantly criticises others in an annoying pedantic fashion
Erubescent
Flushed /reddened like ... She had erubescent cheeks.
Noctambulist
Another word for a person who sleepwalks