spell 3 
(spĕl)
(spĕl)n.
1. A short, indefinite period of time.
2. Informal A period of weather of a particular kind: a dry spell.
3.
a. One's turn at work.
b. A period of work; a shift.
4. Australian A period of rest.
5. Informal A period of physical or mental disorder or distress: a dizzy spell.
6. Informal A short distance.
v. spelled, spell·ing, spells
v.tr.
1. To relieve (someone) from work temporarily by taking a turn.
2. To allow (someone) to rest a while.
v.intr.
1. To take turns working.
2. Australian To rest for a time from an activity.
[From Middle English spelen, to spare, from Old English spelian, to represent, substitute for.]