means a friendly greeting or expression that lets someone know their arrival, presence, or participation is genuinely wanted.

from From Old English wilcuma, a warm little compound: wil- (related to 'will,' meaning desire or pleasure) plus cuma (a guest, one who comes — a cousin of the verb 'come'). So a wilcuma was literally a 'desired comer,' a guest you actually wanted. The first syllable later drifted toward 'well,' nudged by the cheerful sense of welfare and well-wishing, giving us the modern spelling — though the heart of it always meant the guest who came according to your wish.