instransigent

stubborn

levity

humor and frivolity

invective

insulting

misanthropic

hating or having contempt for humankind

pejorative

disparaging or belitting

sentient

conscious and aware

tirade

rant

alacrity

prompt and cheerful

crestfallen

deject/sad/disappointed

germane

revevant and fitting to situation

paramount

superior

inscrutable

unfathomable

substantiate

strengthen with new evidence

plausible

possibly true

assiduous

showing great care