The word “foolish” used in Matthew 25 is the greek word “móros”

Foolish

3474. móros
Strong’s Concordance (Greek)
Definition: dull, stupid, foolish
Usage: (a) adj: stupid, foolish, (b) noun: a fool.
 
3474 mōrós (the root of the English terms, “moron, moronic”) – properly, dull (insipid), flat (“without an edge”); (figuratively) “mentally inert”; dull in understanding; nonsensical (“moronic”), lacking a grip on reality (acting as though “brainless”).
 
NASB Translation
fool (1), foolish (7), foolish things (1), foolishness (1), fools (2).
 
Thayer’s Greek Lexicon
imprudent, without forethought or wisdom (Matthew 25:2f, 8)

The Foolish: Lack Wisdom

Why is there in the hand of a fool the purchase price of wisdom,
Since he has no heart for it?

Why is there in the hand of a fool the purchase price of wisdom,
Since he has no heart for it?
Proverbs 17.16

“fools die for lack of wisdom (heart)”

The lips of the righteous feed many,
But fools die for lack of [e] wisdom (heart).
Proverbs 10.21

“fools despise wisdom and instruction”

The fear of the Lord is the beginning of knowledge,
But fools despise wisdom and instruction.
Proverbs 1.7

“fools hate knowledge”
 
“How long, you [j] simple ones (naive), will you love simplicity?
For scorners delight in their scorning,
And fools hate knowledge.
Proverbs 1.22

“The way of a fool is right in his own eyes”

The way of a fool is right in his own eyes,
But he who heeds counsel is wise.
Proverbs 12.15

The Foolish: Lack Understanding

“you simple (naive) ones, understand prudence,
And you fools, be of an understanding heart“

O you [b] simple (naive) ones, understand prudence,
And you fools, be of an understanding heart.
Proverbs 8.5

“A fool has no delight in understanding”
 
A fool has no delight in understanding,
But in expressing his own heart.
Proverbs 18.2

“But a rod is for the back of him who is devoid (lack) of understanding.”

“But the mouth of the foolish is near destruction.”
 
Wisdom is found on the lips of him who has understanding,
But a rod is for the back of him who [c] is devoid (lack) of understanding.
14 Wise people store up knowledge,
But the mouth of the foolish is near destruction.
Proverbs 10.13-14

“Forsake foolishness and live,
And go in the way of understanding.”

The Way of Wisdom
“Come, eat of my bread
And drink of the wine I have mixed.
6 Forsake foolishness and live,
And go in the way of understanding.
Proverbs 9.5

The Foolish: Speak Foolishness

“a prating (Lit. the foolish of lips) fool will fall (be thrust down or ruined)”

The wise in heart will receive commands,
But [a] a prating (Lit. the foolish of lips) fool will [b] fall (be thrust down or ruined).
Proverbs 10.8

“But the mouth of fools pours forth foolishness.”

The tongue of the wise uses knowledge rightly,
But the mouth of fools pours forth foolishness.
Proverbs 15.2

“the heart of fools proclaims foolishness.”

A prudent man conceals knowledge,
But the heart of fools proclaims foolishness.
Proverbs 12.23

“a fool lays open his folly.”
 
Every prudent man acts with knowledge,
But a fool lays open his folly.
Proverbs 13.16

“whoever spreads slander is a fool.”

Whoever hides hatred has lying lips,
And whoever spreads slander is a fool.
Proverbs 10.18

“what is in the heart of fools is made known.”

Wisdom rests in the heart of him who has understanding,
But what is in the heart of fools is made known.
Proverbs 14.33

“A foolish woman is clamorous (boisterous)”

The Way of Folly
A foolish woman is [b] clamorous (boisterous);
She is simple, and knows nothing.
Proverbs 9.13

The Foolish: Quick-Tempered

“a fool rages and is self-confident.

A quick-tempered man acts foolishly

The simple inherit folly”

A wise man fears and departs from evil,
But a fool rages and is self-confident.
17 A quick-tempered man acts foolishly,
And a man of wicked intentions is hated.
18 The simple inherit folly,
But the prudent are crowned with knowledge.
Proverbs 14.16-18

“A fool’s wrath is known at once”
 
A fool’s wrath is known at once,
But a prudent man covers shame.
Proverbs 12.16

“the foolishness of fools is folly.”

The wealth of the wise is their crown
But the foolishness of fools is folly.
Proverbs 14.14

“the companion of fools will be destroyed.”

He who walks with wise men will be wise,
But the companion of fools will be destroyed.
Proverbs 13.20

“A fool despises his father’s instruction”

A fool despises his father’s instruction,
But he who [b] receives correction is prudent.
Proverbs 15.5

“But he who refuses correction goes (leads) astray.”
 
He who keeps instruction is in the way of life,
But he who refuses correction [d] goes (leads) astray.
Proverbs 10.17

“But the heart of the fool does not do so”

The lips of the wise [c] disperse (spread) knowledge,
But the heart of the fool does not do so.
Proverbs 15.7

“How long will you slumber (lie down), O sluggard?
When will you rise from your sleep?”

The Folly of Indolence
6 Go to the ant, you sluggard!
Consider her ways and be wise,
7 Which, having no captain,
Overseer or ruler,
8 Provides her [e] supplies (bread) in the summer,
And gathers her food in the harvest.
9 How long will you [f] slumber (lie down), O sluggard?
When will you rise from your sleep?
Proverbs 6.6

“My food is to do the will of Him who sent Me, and to finish His work”

“look at the fields, for they are already white for harvest!”

Jesus said to them, “My food is to do the will of Him who sent Me, and to finish His work. 35 Do you not say, ‘There are still four months and then comes the harvest’? Behold, I say to you, lift up your eyes and look at the fields, for they are already white for harvest! 36 And he who reaps receives wages, and gathers fruit for eternal life, that both he who sows and he who reaps may rejoice together.
John 4.34