Synonyms for Go down:

n.

dwindle, crater, shrink. submerge, audit, absence, attend, entrance, enroll, drop out, enrollment, absenteeism, board, attendance. give away, bomb out of, go out, roll over, surrender, appease, concede. call forth, draw, result in, translate, provoke, meet, bring forth, leave. digest, ingestion, metabolize, metabolise, burn, assimilate, absorb, stay down, down. come to, refresh someone's memory, jog someone's memory, remind, trigger, bring back, flood back, recall, awake, bring/call someone/something to mind. break down, burn out, cut out, run down, stop, shut off, break, go off. happen, take place, arrive, come to pass, unfold. deteriorate, descend into, slip into, escalate, spiral, deepen, degenerate. plummet, plunge, lower, lose your balance/footing, slip. cruise, shuttle, ride, hitch, hitchhike, commute, cover. custodial, detention, internment, inside, condemned, captivity, captive, preventive detention, custody. duck, dunk, carry, swim, splash. abase yourself, lower yourself, lose face, debase yourself, demean yourself, shame, fall from grace/favor, come down in someone's estimation/opinion, dishonor, go down in someone's opinion. go down (noun)
decline, go under, crash, wane, set.

v.

change (verb)
crash.
lose, fall (verb)
plunge, succumb, submit, set, submerge, decline, go under.

Other synonyms:

elongated, appease, internment, call forth, preventive detention, attenuated, deteriorate, hitchhike, eclipse, floor-length, orbit, foreshortened, result in, bring forth, full moon, captivity, dunk, descend into, abbreviated, bomb out of, metabolize, fail. custody, full-length, condemned, go in, captive, commute, stay down, submerge, long, burn out, cut out, roll over, plummet. degenerate, wax, assimilate, digest, custodial, slip into. run down, hitch, break down, give away, surrender, shuttle, plunge, submit, concede, lose, go off. deepen, translate, cruise, slip. inside, ride. draw, lower. meet. duck, splash. down. cover. descend
decline, plummet.
fail
break down.
Other relevant words:
slip, shrink, fail, submerge, lose, arrive, plunge, surrender, succumb, plummet, down, dwindle, go off, submit, lower, deteriorate.