угости́ть

fairly common #4375

verbperfective imperfective is угоща́ть

1.
to treat (to food or drink), to entertain (guests), to offer food to
Она́ угости́ла нас чаем с пирого́м.
She treated us to tea and pie.
Usually угостить кого-л. чем-л. - the thing offered is in the instrumental case.
2.
to treat someone to something, to buy someone (a drink)
Я могу́ угости́ть тебя́ у́жином в рестора́не.
I can treat you to dinner at a restaurant.

Examples

Кашеваривший на привале солдат угостил друзей горячей кашей.
The soldier cooking during a halt treated his friends to hot porridge.
Бабушка угостила нас вкусным рахат-лукумом.
Grandma treated us to some delicious Turkish delight.
Молдаванин угостил нас домашним вином.
The Moldovan treated us to homemade wine.
Женщина, стряпавшая пироги, угостила соседей.
The woman who had baked the pies treated her neighbors to some.
Соседка, напекавшая блины, угостила всех детей.
The neighbor who had baked pancakes treated all the children.
Соседка, напекающая печенье каждую субботу, угостила детей.
The neighbor who bakes cookies every Saturday treated the children.
Можно угости́ть тебя сего́дня ужином?
Can I buy you dinner tonight?
Прокоптивший рыбу дед угостил нас ужином.
The grandfather who had smoked the fish treated us to dinner.

Note: Stress change.

Imperative
ты	угости́
вы	угости́те

Active present	-
Active past	угости́вший	having treated, who treated, that treated
Passive present	-
Passive past	угощённый	treated, regaled, entertained (with food/drink)
Gerund present	-
Gerund past	угости́в угостивши	while doing (past)

гости́тьto stay as a guest
verbimperfective
угости́тьto treat (to food or drink); to treat someone to something
verbperfective
отго́ститьto have been a guest
verbperfective
погости́тьto stay as a guest
verbperfective
про́гоститьto stay
verbperfective