What is the true definition of a crest in physics?

[nilic1]

Homework Statement

I was taught that a crest is the section of the wave above rest position.

Homework Equations

The Attempt at a Solution

Now that I am studying Physics at higher level I am getting mixed up as sometimes I encounter situations where a crest is the whole part/section of the wave above rest position but in other cases it is referred to as the highest point of the wave above rest position. So my question is... is a crest a whole section above rest position or just the highest point above it?

 

[MarcusAgrippa]

In colloquial speech, "crest" might refer loosely to the curved section of the wave above the equilibrium position. In physics, we usually mean the point along the wave where the wave reaches its maximum displacement.