noun

The rear surface of the human body from the shoulders to the hips.

he lay on his back

adverb

In the opposite direction from the one that one is facing or travelling towards.

he moved back a pace

backwards,behind one,to one’s rear,rearwards

verb

Give financial, material, or moral support to.

he had a newspaper empire backing him

sponsor,finance,put up the money for,fund,subsidize,underwrite,promote,lend one’s name to,be a patron of,act as guarantor of,support

adjective

Of or at the back of something.

the back garden

rear