交媾

Formal/biological/classical register. Used in zoology (animal mating), classical Chinese medicine, religious/Daoist texts, and academic writing. NOT for everyday speech — use 做爱 (zuò'ài, 'make love') in modern contexts, or 性交 (xìngjiāo) for clinical use.

memory

交 (jiāo) = 'to interact / join', 媾 (gòu) = 'to copulate / form a marital alliance' (also in 婚媾 hūngòu, 'to marry'). The 女 (woman) radical in 媾 marks it as a relationship word. Together: 'to join in coupling'.