Jukai Talks

Upāsaka (masculine) or Upāsikā (feminine) are from the Sanskrit and Pāli words for "attendant". This is the title of followers of Buddhism (or, historically, of Gautama Buddha) who are not monks, nuns, or novice monastics in a Buddhist order, and who undertake certain vows. In modern times they have a connotation of dedicated piety that is best suggested by terms such as "lay devotee" or "devout lay follower".

From Upāsaka on Wikipedia