次甲基（Methine）是指一个和甲烷对应的三价官能团（≡CH）。这个名称通常使用于：

但有时也会用在

 \
 -CH  (三个单键)
 /

• 甲基
• 亚甲基

In chemistry, methine is a trivalent functional group =CH−, derived formally from methane. It consists of a carbon atom bound by two single bonds and one double bond, where one of the single bonds is to a hydrogen. The group is also called methyne or methene; its IUPAC systematic name is methylylidene or methanylylidene