what does "underway" means?

问题描述:

what does "underway" means?
好像是在海上的!
就是“航行中的”的意思!
用英语回答!

underway means that the ship is not at anchor,not mooring,or not made fast to the shore!
在航,指船舶既不系泊,也不锚泊,也不系岸!