Definition of "In" :

noun: a state in midwestern United States

noun: a unit of length equal to one twelfth of a foot

noun: a rare soft silvery metallic element; occurs in small quantities in sphalerite

adjective: currently fashionable

"The in thing to do."

adjective: directed or bound inward

"Took the in bus."

adjective: holding office

"The in party."

adverb: to or toward the inside of

"Come in."