He smote
nakah  (naw-kaw')
to strike (lightly or severely, literally or figuratively)

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also all the firstborn
bkowr  (bek-ore')
firstborn; hence, chief -- eldest (son), firstborn(-ling).

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in their land
'erets  (eh'-rets)
the earth (at large, or partitively a land) -- common, country, earth, field, ground, land, natins, way, + wilderness, world.

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the chief
re'shiyth  (ray-sheeth')
the first, in place, time, order or rank (specifically, a firstfruit) -- beginning, chief(-est), first(-fruits, part, time), principal thing.

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of all their strength
'own  (one)
ability, power, (figuratively) wealth -- force, goods, might, strength, substance.New American Standard Bible
He also struck down all the firstborn in their land, The first fruits of all their vigor.

King James Bible
He smote also all the firstborn in their land, the chief of all their strength.

Holman Christian Standard Bible
He struck all the firstborn in their land, all their first progeny.

International Standard Version
He struck down every firstborn in their land, the first fruits of all their progeny.

NET Bible
He struck down all the firstborn in their land, the firstfruits of their reproductive power.

Aramaic Bible in Plain English
He killed all the firstborn of Egypt, the first of all their offspring.

GOD'S WORD® Translation
He killed all the firstborn sons, the first ones born in the land when their fathers were young.

King James 2000 Bible
He struck also all the firstborn in their land, the first of all their strength.Psalm 105:36
Psalm 105:36 NIV
Psalm 105:36 NLT
Psalm 105:36 ESV
Psalm 105:36 NASB
Psalm 105:36 KJV