The noun rapid has 1 sense (no senses from tagged texts)
1. rapid -- (a part of a river where the current is very fast)
Overview of adj rapid
The adj rapid has 2 senses (first 1 from tagged texts)
1. (21) rapid -- (done or occurring in a brief period of time; "a rapid rise through the ranks")
2. rapid, speedy -- (characterized by speed; moving with or capable of moving with high speed; "a rapid movement"; "a speedy car"; "a speedy errand boy")