Refers to a person's outward manner of being pleasant, approachable, and easy to get along with. Often used in phrases like 愛想がいい (friendly/amiable) and 愛想が悪い (unfriendly/brusque).
彼女はいつも愛想がよくて、誰とでもすぐ仲良くなる。
She is always amiable and quickly becomes friends with anyone.
Polite, often superficial, words or actions meant to please a customer or guest. Frequently appears in service contexts as お愛想 (polite compliments or hospitality). Sense 4 (hospitality/special treatment) is closely related and merged here.
Euphemistic term used by restaurant staff when presenting the bill. Almost always appears as お愛想. Not used by customers to ask for the bill (customers say お勘定).