1. Giving only major written points or parts that are incomplete or vague: The investment advertisement gives a sketchy description of what monetary results might be received for the money.
2. Inadequate, superficial, or lacking in details: The details about the bus accident are still too sketchy to know what really happened.

Jack has only a sketchy idea of how his computer program works.

3. Something which is done quickly without many details: Jillian made a sketchy drawing of the earthquake destruction of the city.