noun
tea strainer
A small mesh utensil used to strain tea leaves when pouring brewed tea into a cup.
急須から注ぐときに茶こしを使うと、茶葉がカップに入らない。
If you use a tea strainer when pouring from the teapot, tea leaves won't get into the cup.
Same meaning and reading; 茶漉し is the full kanji form, while 茶こし is the more common mixed-kana spelling.
Compound of 茶 (cha, 'tea') and 漉し (koshi, 'straining'), from the verb 漉す (kosu, 'to strain').