From Longman Dictionary of Contemporary Englishthink nothing of somethingthink nothing of somethingto think that something is not important and then realize later that it is important I had a pain in my back but thought nothing of it at the time. → think
Examples from the Corpus
thought nothing of it• The Human Piranha, a Harvard graduate, thought nothing of it.• He thought nothing of it at the time.• I thought nothing of it, just that whoever closed the house up had overlooked it. 