WordNet sense 1 (a time for working (after which you will be relieved by someone else)):

go, spell, tour

WordNet sense 2 ((sports) a period of play during which one team is on the offensive):

bout, round

WordNet sense 3 (a circular segment of a curve):

bend, crook, twist

WordNet sense 4 (an unforeseen development):

turn of events

WordNet sense 5 (a movement in a new direction):

turning

WordNet sense 6 (a short theatrical performance that is part of a longer program):

act, bit, number, routine, number

WordNet sense 7 (undergo a change or development):

become

WordNet sense 8 (cause to move around a center so as to show another side of):

turn over

WordNet sense 9 (pass to the other side of):

move around

WordNet sense 10 (to break and turn over earth especially with a plow):

plough, plow

WordNet sense 11 (let (something) fall or spill a container):

release, release

WordNet sense 12 (cause (a plastic object) to assume a crooked or angular form):

deform, flex

WordNet sense 13 (a favor for someone):

good turn

WordNet sense 14 (have recourse to or make an appeal or request for help or information to):

call on

WordNet sense 15 (go sour or spoil):

ferment, sour, work, ferment

WordNet sense 16 ((game) the activity of doing something in an agreed succession):

play

WordNet sense 17 (undergo a transformation or a change of position or action):

change state

WordNet sense 18 (change to the contrary):

reverse, change by reversal

WordNet sense 19 (pass into a condition gradually, take on a specific property or attribute; become):

grow

WordNet sense 20 (twist suddenly so as to sprain):

rick, sprain, wrench, wrick