Verb (used with object), : The presence of two large leather sofas seemed to masculinize the whole room.    From Dictionary.com. 

So pre-natal exposure to excess testosterone will partly masculinise female neurology.    From Wordnik.com.  [BiGender and the Brain] Reference

Those born with 5ARD or 17BHDD are feminised to some degree at birth, and masculinise to some degree at puberty.    From Wordnik.com.  [BiGender and the Brain] Reference

“We think that these genetic differences might reduce testosterone action and under masculinise the brain during foetal development”, said researcher Lauren Hare.    From Wordnik.com.  [Genetic link to gender identity?] Reference

Leader of the study, Professor Vincent Harley has speculated that this genetic variation might reduce testosterone action and "under-masculinise" or feminise the brain during foetal development.    From Wordnik.com.  [Research reveals biological basis of Trans-sexuality] Reference

Benjamin's Syndrome is a form of intersexuality in which the brain of a person with XY chromosomes fails to masculinise for some reason, or the brain of a person with XX chromosomes does masculinise there may be many ways in which this can happen.    From Wordnik.com.  [A Reply from a guy I used to know] Reference

Of man there is little here: therefore do their women masculinise themselves.    From Wordnik.com.  [Thus Spake Zarathustra A book for all and none] Reference

By destroying these particular instincts, that is to say by attempting to masculinise woman, and to feminise men, we jeopardise the future of our people.    From Wordnik.com.  [Thus Spake Zarathustra A book for all and none] Reference

Confirming the above claim, Prince Henry's Institute researcher Lauren Hare said, "We think these genetic differences might reduce testosterone action and under-masculinise the brain during foetal development.    From Wordnik.com.  [xml's Blinklist.com] Reference