1.
kitchen sink
The sink area in a kitchen, including the basin and the surrounding counter space used for washing dishes and food preparation.
流しに皿を置く。
I put the plates in the sink.
流しの排水口が詰まってしまった。
The kitchen sink drain got clogged.
食べ終わった食器は流しに持っていってね。
Please bring the used dishes to the sink when you're done eating.
2.
cruising (for customers)
A taxi driving around without a passenger, looking to pick someone up. Also used for street musicians or performers who move from place to place.
流しのタクシーを拾う。
I'll hail a cruising taxi.
この辺りは流しのタクシーが多いので、すぐ捕まる。
There are many cruising taxis around here, so you can catch one quickly.
流しの演奏家が店を回って歌っていた。
A roaming musician was going around shops singing.
Derived from the verb 流す (to let flow). For sense 1, the word originally referred to the drain channel in traditional Japanese kitchens. In modern usage, 台所の流し specifically means the kitchen sink. The more technical term is 流し台 (sink unit/counter). For sense 2, 流しのタクシー is the standard phrase for a taxi looking for fares on the street, as opposed to one waiting at a taxi stand (駅前のタクシー乗り場).