Both young men
bachuwr  (baw-khoor')
participle passive of 977; properly, selected, i.e. a youth (often collective) -- (choice) young (man), chosen, hole.

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and maidens
bthuwlah  (beth-oo-law')
a virgin (from her privacy); sometimes (by continuation) a bride; also (figuratively) a city or state -- maid, virgin.

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old men
zaqen  (zaw-kane')
old -- aged, ancient (man), elder(-est), old (man, men and...women), senator.

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and children
na`ar  (nah'-ar)
babe, boy, child, damsel (from the margin), lad, servant, young (man).New American Standard Bible
Both young men and virgins; Old men and children.

King James Bible
Both young men, and maidens; old men, and children:

Holman Christian Standard Bible
young men as well as young women, old and young together.

International Standard Version
young men and young women alike, along with older people and children.

NET Bible
you young men and young women, you elderly, along with you children!

Aramaic Bible in Plain English
Boys and virgins, old men and young men,

GOD'S WORD® Translation
young men and women, old and young together.

King James 2000 Bible
Both young men, and maidens; old men, and children:Psalm 148:12
Psalm 148:12 NIV
Psalm 148:12 NLT
Psalm 148:12 ESV
Psalm 148:12 NASB
Psalm 148:12 KJV