When labourers cannot utilize their capabilities fully and for certain period accept less capable job they are said to be underemployed. For example, a computer engineer taking up job in a garage.
When a labourer is willing and ready to work for certain years or days but gets work for less number of years or days even then he is said underemployed.
For example, a worker working in industry or agricultural land gets work only for 5 hours instead of 8 hours then he is said to underemployed.
Seasonal unemployment seen in agriculture sector in rural India is an example of underemployment the seasonal unemployment. The labour in agriculture sector gets work only during sowing and harvesting season and so he remains unemployed rest of the time.
Another reason for this type of unemployment is that Indian agriculture is primarily based on monsoon.
Hence, areas where irrigational facilities are not well developed, people belonging to agriculture sector face seasonal unemployment.