This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. The act of making masculine.

n. the abnormal development of male sexual characteristics in a female (usually as the result of hormone therapies or adrenal malfunction)

"Today's high cesarean rates are due in part to the "masculinization" of birth environments, he added."

ontogeny    development    ontogenesis    maturation    growing