Wiktionary
alt. Work done where the worker is hired and paid one day at a time, with no promise that more work will be available in the future. n. Work done where the worker is hired and paid one day at a time, with no promise that more work will be available in the future.
Wikipedia
Day labor (or day labour in Commonwealth spelling) is work done where the worker is hired and paid one day at a time, with no promise that more work will be available in the future. It is a form of contingent work.
Usage examples of "day labor".
You tell the Teamster picket boss that the day labor joint downtown sent you out, muscle for a buck an hour.
In good years, of course, such people found day labor and managed, but in bad years even the prosperous stared into the gaunt face of hunger.
I knew this collection of people was essentially random, just those who had been looking for work when this job was available, but the grueling day labor and the songs by night unified it rapidly.
Hours like this would mean a strike in time of peace when men earn ten francs a day for day labor.