Merriam-Webster's Collegiate® Dictionary, 11th Edition
WELCOME
I. transitive verb (welcomed; welcoming)
Etymology: Middle English, from Old English welcumian, wylcumian, from wilcuma, noun Date: before 12th century to greet hospitably and with courtesy or cordiality, to accept with pleasure the occurrence or presence of , welcomer noun
II. interjection see: will
Date: 12th century
— used to express a greeting to a guest or newcomer upon arrival
III. adjective
Date: 12th century
received gladly into one's presence or companionship , giving pleasure ; received with gladness or delight especially in response to a need , willingly permitted or admitted ,
4. — used in the phrase “You're welcome” as a reply to an expression of thanks welcomely adverb welcomeness noun
IV. noun
Date: 1525
a greeting or reception usually upon arrival , the state of being welcome