Antonym: noun: a word that means the opposite of another word.
Taken: past participle of take
Antonym of Taken: Given: past participle of give.
Greedy.
ending
I wonder if you are looking for the near synonym - not antonym - ultimate.
start, beginning
beginning beforehand inception
graphic
Gift
hesitate
Objectivity
The best brand of watches beginning with g is G-Shock
g
gentle.