noun / adjective

lunatic

LOO-nuh-tik/ˈluːnətɪk/

Showing wildly irrational or reckless behavior.

The lunatic plan piles an unstable tower of chairs onto a tiny handcart.

A wildly foolish adult tries to transport an impossibly tall unstable stack of empty chairs on a tiny handcart, ignoring the obvious imbalance; no injuries, no mental-health stereotype.

Etymology

The moon connection reflects an old belief that changes of the moon caused recurring mental disturbance. The adjective meant “moon-struck,” and the noun broadened from someone with lucid intervals to a person considered mentally unstable.

In context

The Enchanted Archive4:47

if he's a merchant and if the guys behind him are his guards. The man can barely stammer out a yes, wondering if this lunatic is going to snap him in half

[Part 1] A savage BARBARIAN forced his way into her carriage and now ROYALTY is TERRIFIED

More examples

Only a lunatic would drive that fast on icy roads.
We cannot keep working at this lunatic pace.
She calls him a lunatic for betting his entire paycheck.

Forms

lunatic · lunatics

lunacy noun — Wildly irrational or reckless behavior.

Similar words

reckless: Emphasizes disregard for danger rather than wildly irrational behavior.
irrational: Emphasizes lack of sound reasoning, without necessarily suggesting recklessness.
fool: Describes someone lacking judgment, not necessarily acting wildly or dangerously.