adj
Having little depth; significantly less deep than wide.
This crater is relatively shallow.
Sauté the onions in a shallow pan.
Extending not far downward.
The water is shallow here.
Concerned mainly with superficial matters.
It was a glamorous but shallow lifestyle.
Lacking interest or substance; flat; one-dimensional.
The acting is good, but the characters are shallow.
Not intellectually deep; not penetrating deeply; simple; not wise or knowing.
shallow learning
The king was neither so shallow, nor so ill advertised, as not to perceive the intention of the French king.
noun
A shallow portion of an otherwise deep body of water.
The ship ran aground in an unexpected shallow.
A swift stream is not heard in the channel, but […]upon shallows of gravel.
A fish, the rudd.
A costermonger's barrow.
You might have gone there quite as easily, and enjoyed yourself much more, had your mode of conveyance been the railway, or a hansom, or even a costermonger's shallow.
verb
To make or become less deep.
The shallowing of Cenozoic age-frequency curves from tropics to poles thus appears to reflect the decreasing probability for genera to reach and remain established in progressively higher latitudes ( 9 ).