marked by an orderly, logical, and aesthetically consistent relation of parts
"a coherent argument"
(physics) of waves having a constant phase relation
"The laser beam remained coherent, ensuring that all its light waves maintained a constant phase relation across the entire spectrum."
Unified; sticking together; making up a whole.
"The scattered puzzle pieces finally formed a coherent image once I found the missing corner."
In plain English: Coherent means something is clear, logical, and easy to follow without confusing jumps or gaps.
"The student gave a coherent presentation that was easy to follow from start to finish."
Usage: Use coherent to describe ideas, speech, or writing that are logically connected and easy to follow rather than disjointed. This word applies specifically to the clarity of thought or expression, not to physical objects stuck together by glue.
The word comes from the Old French coherant, which was borrowed from the Latin cohaerens. It originally described things sticking together or remaining united before entering English with that same sense of logical connection.