A person who has converted to a religion.

“They were all converts to Islam.”

A person who is now in favour of something that he or she previously opposed or disliked.

“I never really liked broccoli before, but now that I've tasted it the way you cook it, I'm a convert!”

The equivalent of a conversion in rugby

To transform or change (something) into another form, substance, state, or product.

“A kettle converts water into steam.”

To change (something) from one use, function, or purpose to another.

“He converted his garden into a tennis court.”

To induce (someone) to adopt a particular religion, faith, ideology or belief (see also sense 11).

“They converted her to Roman Catholicism on her deathbed.”