表弟

biǎodì
younger male cousin through a female relative

CEDICT

cousin (mother's sibling's or father's sister's son younger than oneself)

Wiktionary

称谓。用来称呼姑妈、姨妈、舅舅的儿子，且年纪比自己小。

重編國語辭典

父亲的姐妹的儿子或母亲的兄弟姐妹的儿子，年龄小于自己

維基詞典

Entry Composition

=1 表 biǎo
  1. exterior surface
  2. family relationship via females
  3. to show (one's opinion)
  4. a model
  5. a table (listing information)
  6. a form
  7. a meter (measuring sth)
=1 表 biǎo
  1. watch (timepiece)
  2. meter; gauge
2 弟 dì
  1. younger brother
  2. junior male
  3. I (modest word in letter)

Containing this entry

表弟妹 biǎodìmèi
  1. wife of younger male cousin via female line
  2. younger cousins via female line
表弟媳 biǎodìxí wife of younger male cousin via female line