Needful means necessary or required. When something is needful, you genuinely need it to meet an important requirement or fulfill an essential purpose. A winter coat is needful in Minnesota because you need protection from the cold. Medicine is needful when you're sick because your body requires it to heal.

The word appears often in older books and formal contexts. In Little Women, the March family does “what is needful” to help their sick neighbor, meaning they do what's required, not just what's convenient. You might hear someone say “I'll do the needful” to mean they'll take care of what needs to be done.

While needful and necessary mean similar things, needful can carry a warmer, more personal feeling. Food is necessary for survival (a cold fact), but a hot meal after a long day feels needful (something your body and spirit require). The word reminds us to distinguish between things we genuinely need and things that merely catch our attention or interest.