impregnable

not able to be conquered 

ant:vulnerable 

xenophobia

an intense dislike or fear for strangers

inherent

essential

ant:extrinsic

irreverent

disrespectful

ant:worshipful

subjugate

to dominate

ant:free

expedite

to increase the rate of progress

ant:retard

filibuster

to block a bill from becoming law

pristine

pure

ant:defiled

pithy

full of meaning 

ant:verbose

invective

an insult or abuse in speech

ant:praise

prodigal

reckless wasteful

ant:prudent

pliable

easily bent or flexible

ant:rigid

torpid

losing motion lacking energy

ant:energetic

tenuous

not dense or thick

ant:strong