noun
filter paper
Paper used for filtration, such as in coffee making or laboratory work.
コーヒーを淹れるときは漉し紙を使います。
I use filter paper when brewing coffee.
Compound of 漉し (koshi, 'straining, filtering', from verb 漉す kosu) + 紙 (kami, 'paper'). The reading kami becomes gami due to rendaku.