Lookups of radicalize spiked the week of December 7, 2015, as it was used in two developing stories.
The first use of radicalize we saw this week was in news surrounding the mass shooting in San Bernardino, CA. The motive of the shooters, a Muslim couple, is still largely unknown, though FBI assistant director David Bowdich told the press on December 7, "We believe that both were radicalized and had been for some time."
The second use of radicalize was made by Philadelphia mayor Michael Nutter in a December 9 story about anti-Islamic vandalism against a mosque in Philly. He brought up Donald Trump's latest statement that the U.S. should ban Muslims from entering the country by saying, "Trump is literally trying to radicalize Americans against Muslims, and that's not what America is about."
Both uses of radicalize refer to making someone radical—that is, doing or saying something that causes a person to adopt extreme views, beliefs, or political ideologies. Interestingly, the word radical comes from radix, a Latin word that means "root," yet the meaning of radical that radicalize draws on it about rejecting the usual or traditional.
We tend to think of the word radicalize with regard to religious ideology, but that has more to do with the news cycle than the word itself. Radicalize goes back to the early 1800s and has been used of everyone from abolitionists to Vietnam protestors.