lemma
noun /ˈlemə/
  /ˈlemə/
(plural lemmas, lemmata 
 /ˈlemətə/
  /ˈlemətə/
)- (specialist) a statement that is assumed to be true in order to test the truth of another statement引理;辅助定理 
- (linguistics语言学 词根,词元(词的基本形式,如名词单数或动词的不定式形式) 
词源late 16th cent.: via Latin from Greek lēmma ‘something assumed’; related to lambanein ‘take’.