On a route to some place.

synonym: on the way.

Roget 270: from hand to hand, from pillar to post.    on the way, by the way; on the road, on the wing, under way, in transit, on course; as one goes; in transitu [Lat.], en route, chemin faisant [Fr.], en passant [Fr.], in mid progress, in mid course.    ... show more

Roget 266: on foot, on horseback, on Shanks's mare; by the Marrowbone stage; in transitu [Lat.] etc. 270; en route etc. 282.