'legitimise' is a correct and usable word in written English.
You can use it when you want to refer to the act of legitimizing someone or something. For example: "The government has taken steps to legitimise the new laws."
In 1999 the compliant parliament voted for Niyazov to become president for life, and in 2002, he used an alleged assassination attempt to legitimise a far-reaching crackdown on political opponents.
He had also obtained a PhD in Islamic studies from the Islamic University of Baghdad, and would draw on both to legitimise his unprecedented claim to anoint himself caliph of the Islamic world in July 2014, which realised a sense of destiny evident in the prison yard a decade earlier.
To make things worse, it was not a myth copied and perpetuated solely by the tabloids; the broadsheets were equally responsible for repeating it, and perhaps did more to legitimise it than the tabloids.
It's a false solution that's just going to be used by to coal industry to legitimise new coal power".
"The question is whether he can legalise it and legitimise it".
It is reasonable to wonder if it might help legitimise the sort of street harassment that projects like Everyday Sexism have so well documented, as that drunken crowd spills out onto the streets.
"President Zuma's congratulations are not only extremely premature, given the very serious irregularities that have been noted in the elections, but shamefully legitimise undemocratic practices during elections, and send a message that significant irregularities will be tolerated by his administration".
How can Javid legitimise touts, making access to the arts prohibitively expensive for many, and yet also be the culture secretary responsible for the simple act of getting people through the doors to see stuff?
A member of parliament said at the time that the law was adopted to "legitimise" Haftar, who calls himself chief of the Libyan National Army.
At one point, as he was assailing the US for attempting to "legitimise an illegal affair", an airport announcement broke in.
Support the human rights organisations determined to shut down every avenue by which the regime can legitimise itself.
