The Oxford Thesaurus An A-Z Dictionary of Synonyms INTRO ...

following, pursuing, chasing, US in back of: Here come the
hounds at the back of the fox. You were at my back in the queue
a minute ago. 6 behind the back of or behind someone's back.
surreptitiously, secretly, clandestinely, privately, furtively,
sneakily, slyly; treacherously, traitorously, perfidiously,
deceitfully, insidiously: Graham is always telling tales about
you behind your back. 7 break the back of. a overcome, master:
Now that he's broken the back of that problem he can get on with
his work. b US crush, ruin, bankrupt, destroy, defeat, vanquish,
Colloq break: The government has tried on many occasions to
break the back of the Mafia operation. 8 on (someone's) back.
US weighing (down) on or upon (someone), burdening (someone),
lodged with (someone), resting with (someone): The
responsibility for the decision is on your back. 9 turn one's
back on or upon. abandon, forsake, ignore, disregard, repudiate,
reject, cast off, disown, deny: He turned his back on her when
she needed him most. 10 with one's back to or against the wall.
hard pressed, struggling (against odds), without hope, with
little or no hope, helpless, in dire straits, in (serious)
trouble: After the stock-market crash, some brokers found
themselves with their backs to the wall.
--adj. 11 rear; service, servants': Both back tyres are flat.
Please use the back staircase from now on. 12 US and Australian
and New Zealand outlying, remote, isolated, distant;
undeveloped, primitive, raw, rough, uncivilized: They raised
three boys in the back country, and all of them became doctors.
13 in arrears, overdue, past due, late; behindhand: The tax
inspector has advised me that I owe thousands in back taxes.
--adv. 14 to or toward(s) the rear, rearward(s), backward(s);
away: We beat back the enemy in severe hand-to-hand fighting. I
accepted his offer at once, lest he should draw back. Get back
from the edge! 15 in return or repayment or requital or
retaliation; again: I'll pay you back when I have the money.
She gave him back as good as he had given. 16 ago, in time(s)
past: Two generations back, his was the finest house in the
town. 17 behind, behindhand, in arrears, overdue: We are a
week back in the rent. 18 go back on. renege, fail; deny,
disavow, break, repudiate: He has gone back on his promise to
send the payment on the first of every month.
backbone n. 1 spine, spinal column: He's much better since the surgery