Underdeveloped (adjective)

1. Not fully developed or mature; not advanced.
2. Not having had the economic, social, or industrial growth normal for a country or area.

Origin:

Composed of the prefix "under-" meaning below or less than and the past participle of the verb "develop" meaning to grow or mature.

Examples:

1. His muscles were underdeveloped from a lack of exercise.
2. The small country was underdeveloped with little infrastructure and limited resources.
3. He had an underdeveloped sense of humor and couldn't understand the jokes.
4. The company's products were underdeveloped and not yet ready for market.
5. The underdeveloped areas of the city lacked basic amenities such as sewage systems and running water.