雄(おす)and 雌(めす) this two words are for animals. But In encyclopedia or science book you will see those words in katakana, オス・メス. This is Japanese writing rules. And also For human, 男(おとこ)and 女(おんな) which is male and female. If it’s plants we commonly use 雄花(おばな)、雌花(めばな). Depends on objects you gonna describe, vocabulary gonna be changed in Japanese. むずかしいですね!でも、いい質問です!