To form mental images of
To experience dreams or daydreams
What does he fantasize doing with you?
She was in his world now, offering him something he'd allowed himself to fantasize about more than once.
It was useless for her to fantasize about Xander, not when a couple dozen women who belonged on the covers of magazines were gathered around.
Women are also more likely to fantasize about things they've heard about, but never tried including ménage, group sexual experiences, voyeurism and bondage.
Take a drive on the 17-Mile Drive and fantasize what it takes to get an address on the road.