кача́ться

fairly common #4288C2

verbreflexiveimperfective perfective is качну́ться

1.
to swing, to rock
Де́ти кача́лись на каче́лях.
The children were swinging on the swings.
Of a person moving back and forth on a swing, rocking chair etc.
2.
to sway, to swing, to rock
Ве́тки кача́лись на ве́тру.
The branches were swaying in the wind.
Of branches, a lamp, a boat, a pendulum.
3.
to stagger, to reel, to sway
Он кача́лся от уста́лости.
He was swaying with exhaustion.
Of an unsteady person - from tiredness illness or drink.
4.
to work out (with weights), to pump ironsports
Он ка́ждый день кача́ется в спортза́ле.
He works out at the gym every day.
Colloquial.

Examples

Лодка, пододвигающаяся к берегу, медленно качалась на волнах.
The boat moving closer to the shore was slowly rocking on the waves.
Он пьяно улыбался и качался
He smiled drunkenly and swayed.
Вайя пальмы качалась на ветру.
The palm frond swayed in the wind.
На волнах качалось одинокое судёнышко.
A lone little boat bobbed on the waves.
Маленькая лодчонка качалась на волнах.
The little boat rocked on the waves.
Её запрокинувшаяся голова качалась при каждом шаге.
Her head, tilted back, bobbed with every step.
Ветка, свешивающаяся над рекой, качалась от ветра.
The branch hanging over the river swayed in the wind.
На ветру качался старый фонарь, болтавшийся на проводе.
An old lamp hanging from a wire swayed in the wind.

Imperative
ты	кача́йся
вы	кача́йтесь

Active present	кача́ющийся	swinging, rocking, swaying, wobbling
Active past	кача́вшийся	swaying, swinging, rocking
Passive present	-
Passive past	-
Gerund present	кача́ясь	while doing (present)
Gerund past	кача́вшись	while doing (past)

кача́тьto rock; to shake (one's head); to pump; to download
verbimperfective
вкача́тьto pump in; to pump in (money); to upload
verbperfective
укачатьto rock to sleep; to make sick (from motion); to rock back and forth
verbperfective
вы́качатьto pump out
verbperfective
докача́тьto pump up (fully); to finish downloading
verbperfective