The reading しっき (shikki) uses the On'yomi of both 漆 (shitsu → shi) and 器 (ki), with a common sound change (rendaku) making it しっき. うるしぬり (urushinuri) is a different word using Kun'yomi. 漆器 refers to items made from wood or other materials, coated with layers of lacquer to create a durable and often decorative finish.

漆（シツ）と器（キ）のOn'yomiが連濁した読みが「しっき」です。うるしぬり（漆塗り）は訓読みで別の言葉です。漆器は、漆を塗って作られた美しい器物のことです。