to work extremely hard

कड़ी मेहनत करना

English Usage: They toiled all day under the scorching sun.

Hindi Usage: उन्होंने तेज धूप में पूरा दिन मेहनत की।

hard work or labor

कड़ी मेहनत

English Usage: His toils in the field were finally rewarded.

Hindi Usage: खेत में उसकी मेहनत का अंततः फल मिला।