Adverb
1. backward
2. backwards, rearward, rearwards, backward
3. in reply
Adjective
1. back
2. backmost, hindermost, hindmost, rearmost, rear, rearward, aft, posterior, hind
3. hinder, posterior, noncurrent
Noun
1. dorsum
2. body part, rear
3. side, rear
4. position, place, football player
5. footballer, spinal column
6. vertebral column, spine, backbone, rachis, skeletal structure, binding
7. book binding, cover, protective covering, protective cover, protection, cloth covering
8. backrest
9. support, position
Verb
1. endorse
2. indorse, plump for, plunk for, support, approve, O.K., okay, sanction, travel
3. go, move, locomote, back up, back off, back down, back out, second
4. endorse, indorse, support, back up, finance
5. lie
6. bet on
7. gage, stake, game, punt, bet, wager, play, switch
8. change over, shift, back up
9. confirm, corroborate, sustain, substantiate, support, affirm, strengthen