cross-cousin

(anthropology) The child of one's father's sister or of one's mother's brother; a cousin related via opposite-gender siblings rather than same-gender ones (the latter being a parallel cousin).

Japanese Meaning

父の姉（叔母）や母の兄（伯父）から生まれるいとこ。すなわち、対となる異性の兄弟姉妹を介して関係するいとこ（parallel cousinとは異なる）

What is this buttons?

Her cross-cousin arrived at the ceremony carrying a gift.

Google Translation / DeepL Translation

彼女の父の姉妹の子、または母の兄の子が式に贈り物を持ってやって来た。

Details

Sense（1）

(anthropology) The child of one's father's sister or of one's mother's brother; a cousin related via opposite-gender siblings rather than same-gender ones (the latter being a parallel cousin).