洗せん面めん台だい

せ

ん

め

ん

だ

い

Meanings

Refers to a fixed basin with a counter, typically found in bathrooms or washrooms. Often includes a mirror and storage.

洗せん面めん台だいで顔かおを洗あらうto wash one's face at the washbasin
朝あさ起おきたらまず洗せん面めん台だいで顔かおを洗あらう。
When I get up in the morning, I first wash my face at the washbasin.
洗せん面めん台だいに立たつto stand at the washbasin
彼かれは洗せん面めん台だいに立たって歯はを磨みがいていた。
He was standing at the washbasin brushing his teeth.
洗せん面めん台だいを掃そう除じするto clean the washbasin
週しゅう末まつに洗せん面めん台だいを掃そう除じした。
I cleaned the washbasin over the weekend.

洗せん面めん器きN2
洗面器 is a small portable basin you carry water in, while 洗面台 is a fixed sink built into a bathroom counter.

洗せん面めん所じょN2
洗面所 refers to the whole washroom or lavatory, while 洗面台 is just the sink fixture inside it.
流ながし台だいN3
流し台 is a kitchen sink, whereas 洗面台 is a bathroom washbasin, so the two are easy to mix up by shape but differ by location.
洗せん面めん器きN2
洗面器 is a basin (often portable) used for washing, while 洗面台 refers to the fixed sink unit with a mirror that holds such a basin.
シンク
シンク usually refers to a kitchen (or utility) sink, while 洗面台 specifically means the bathroom washbasin used for washing your face and hands.

台だいN4
stand; base; platform; table; rack · setting (of a gem); mounting · stock (in grafting) · counter for machines and vehicles · level; mark; range; decade (of one's life) · tall building (with a fine view); observation platform · plateau; heights

Compound of 洗面 (washing one's face) + 台 (stand, platform). The reading is standard on'yomi.