The letter s by itself is never an entire syllable - not nes-s-ary. Learn to hear the "c" in the word - ne-ces-sary.
The antonym would be unnecessary. Or irrelevant, useless, beside the point, etc.
googkle
Yes if nessary
is a stench pipe nessary
3
It is not nessary but it posible.
Yes
2
No degree nessary
so they can work
The antonym of the word 'synonym' is 'antonym'.
an opaqe objecta sorce of light
Many people feel it is not. Matter of opinion.