Webster's Revised Unabridged Dictionary · 1913

Shallow

Shallow , adjective

[Old English schalowe, probably originally, sloping or shelving; compare Icelandic skjālgr wry, squinting, Anglo-Saxon sceolh, Dutch & German scheel, Old High German schelah. Compare Shelve to slope, Shoal shallow.]

1.
Not deep; having little depth; shoal.
Shallow brooks, and rivers wide. — Milton
2.
Not deep in tone. [Rare]
The sound perfecter and not so shallow and jarring. — Bacon
3.
Not intellectually deep; not profound; not penetrating deeply; simple; not wise or knowing; ignorant; superficial; as, a shallow mind; shallow learning.
The king was neither so shallow, nor so ill advertised, as not to perceive the intention of the French king. — Bacon
Deep versed in books, and shallow in himself. — Milton

Shallow , noun

1.
A place in a body of water where the water is not deep; a shoal; a flat; a shelf.
A swift stream is not heard in the channel, but upon shallows of gravel. — Bacon
Dashed on the shallows of the moving sand. — Dryden
2.
(Zoology) The rudd. [Provincial English]

Shallow , transitive verb

To make shallow. — Sir T. Browne

Shallow , intransitive verb

To become shallow, as water.