degree of psychological or intellectual profundity
"The critic praised the novel for its surprising depth, noting how it explored complex themes without ever feeling heavy-handed."
the intellectual ability to penetrate deeply into ideas
"Her analysis of the novel revealed a depth that allowed her to uncover themes most readers completely missed."
the attribute or quality of being deep, strong, or intense
"the depth of his breathing"
"the depth of his sighs"
"the depth of his emotion"
the vertical distance below a surface; the degree to which something is deep
"The diver checked her depth gauge before descending into the murky blue water."
In plain English: Depth is how far down something goes from the top surface to the bottom.
"The diver checked the depth before descending into the ocean."
Usage: Use depth to describe how far down from a surface an object extends or how intense an abstract quality is, such as the depth of water or the depth of emotion. Avoid using it to refer to width or length, which are horizontal measurements.
The word depth comes from the Old English term dīepþ, which was formed by adding an abstract suffix to the word for "deep." It entered Middle English as depthe and has retained its original meaning throughout its history.