1. Fig. a quick and careless treatment. (A noun. Said of an act of cleaning, studying, examination, or appraisal.) Bill gave his geometry the once-over-lightly and then quit studying. Ann, you didn't wash the dishes properly. They only got a once-over-lightly.
2. Fig. cursory; in a quick and careless manner. (An adverb.) Tom studied geometry once-over-lightly. Ann washed the dishes once-over-lightly.