dull

Lacking the ability to cut easily; not sharp.

All these knives are dull.

Boring; not exciting or interesting.

He sat through the dull lecture and barely stayed awake.

"You are very dull this morning, Sheriff," said the youngest daughter of the house, who, being the baby and pretty, had grown pettishly privileged in speech.

Not shiny; having a matte finish or no particular luster or brightness.

Choose a dull finish to hide fingerprints.

a dull fire or lamp;  a dull red or yellow;  a dull mirror

Not bright or intelligent; stupid; having slow understanding.

She is not bred so dull but she can learn.

dull at classical learning

Sluggish, listless.

This people's heart is waxed gross, and their ears are dull of hearing.

O, help my weak wit and sharpen my dull tongue.

To render dull; to remove or blunt an edge or something that was sharp.

Years of misuse have dulled the tools.

This […] dulled their swords.

To soften, moderate or blunt; to make dull, stupid, or sluggish; to stupefy.

He drinks to dull the pain.

Those [drugs] she has / Will stupefy and dull the sense a while.

To lose a sharp edge; to become dull.

A razor will dull with use.

To render dim or obscure; to sully; to tarnish.

A surname. of Scottish and German origin.