Of a light, or an illuminated object: Faintly luminous, not clear; somewhat dark, obscure, shadowy, gloomy. The opposite of bright or clear.

Of the night or a part of the night: not illuminated by the sun; characterized by (relative) absence of light. Frequently predicative, with…

Of water, wine, etc., Troubled, turbid, muddy, thick; of air, etc., Misty, murky, cloudy, not clear; in quot. 1400, dim, dusky.

Of something luminous or illuminated: lacking in brightness or brilliancy; faint in lustre, dim.

Of or in reference to physical qualities, as colour or luminosity, sound, taste: Not clear, bright, vivid, or intense; obscure, dim; indistinct…

Not fully clear or pure; cloudy, obscure, opaque. Also: not easily discernible, indistinct. Also figurative.

(un-, prefix1 affix 1.)

Dim, obscure, faint. Obsolete. rare.

Not light or bright; dark.

Not clear in appearance; impure. Not clear or pure in colour or appearance; (spec. of light) clouded, opaque; (spec. of a colour) dull…

Applied to the (light of) heavenly bodies, etc.: Faint, sickly, partially obscured. Also, of white objects, etc.: Dull, lustreless.

Not shining; dull, dark; = opaque, adj. 1b. Obsolete.

Covered with or as if with a film; dim, hazy, clouded.

Non-luminous, opaque, dark.

figurative. Resembling or likened to twilight; dim, indistinct.

Lacking brightness; dull, dim.

That emits no rays of light; dull. Also in figurative contexts.

Of an object or surface: not reflecting or emitting light; not shining or lustrous. Also figurative. Now rare.

Veil-like; diaphanous.

Of air, smoke, clouds, etc.: Thick, dense; dark.

Not clear or bright.

Not effulgent; wanting brilliance.

transferred. Dim, misty, indistinct in outline.

Not shining or resplendent.

weakly luminous, dim; (Astronomy) of lower luminosity than is typical.

figurative. Originally of light: watery, faint; lacking real substance or strength; wishy-washy.

Without brightness.