The Japanese word for May is
5月

ごがつ - gogatsu

Japanese Definition

May
1. 名詞. 五月、グレゴリオ暦において、第五の月、31日で構成される。
2. 名詞. 女性の名前。(別綴字Mae)

五月
1. n. May
2. n. (poetic) May
3. n. (botany) , a kind of azalea native to Japan (so named because it usually blooms in May)
4. n. Usage: As with many terms that name organisms, this term is often spelled in katakana, especially in biological contexts, as サツキ When spelled in kanji, the azalea sense may be more often
5. n. Usage: The term gogatsu is the most common term for the month of May in modern Japanese. The synonyms satsuki and sanaezuki are archaic and may be used in historical or poetic contexts.