guest

guest /ˈgɛst/ noun
plural guests
guest
/ˈgɛst/
noun
plural guests
Britannica Dictionary definition of GUEST
[count]
1 
: a person who is invited to visit or stay in someone's home
2 
: a person who is invited to a place or an event as a special honor
3 
: a customer at a hotel, restaurant, etc.
4 
: a usually well-known person who is invited to appear or perform on a program, at an event, etc.
— often used before another noun

be my guest

— used in speech to say that someone is welcome to do or take something