15 Heb “Rephaim,” a term that refers to those who occupy the land of the dead (see Isa 14:9; 26:14, 19).
16 Heb “in Abaddon,” a name for Sheol. The noun is derived from a verbal root meaning “to perish,” “to die.”
17 Heb “known.”
18 Heb “darkness,” here a title for Sheol.
19 Heb “forgetfulness.” The noun, which occurs only here in the OT, is derived from a verbal root meaning “to forget.” The rhetorical questions in vv. 10–12 expect the answer, “Of course not!”

In other versions

Do you work wonders for the dead?

Do the departed rise up to praise you? Selah

Is your steadfast love declared in the grave,

or your faithfulness in Abaddon?

Are your wonders known in the darkness,

or your righteousness in the land of forgetfulness?

Do you show your wonders to the dead?

Do their spirits rise up and praise you?

Is your love declared in the grave,

your faithfulness in Destruction?

Are your wonders known in the place of darkness,

or your righteous deeds in the land of oblivion?

Do you work wonders for the dead?

Do departed spirits rise up to praise you?

Selah

Will your faithful love be declared in the grave,

your faithfulness in Abaddon?

Will your wonders be known in the darkness

or your righteousness in the land of oblivion?

Are your wonderful deeds of any use to the dead?

Do the dead rise up and praise you?

Interlude

Can those in the grave declare your unfailing love?

Can they proclaim your faithfulness in the place of destruction?

Can the darkness speak of your wonderful deeds?

Can anyone in the land of forgetfulness talk about your righteousness?

Do you work wonders for the dead?

Or do the departed spirits rise up to praise you? Selah

Is your loyal love told in the grave,

or your faithfulness in the underworld?

Are your wonders known in the darkness,

or your righteousness in the land of forgetfulness?

Wilt thou shew wonders to the dead?

Shall the dead arise and praise thee? Selah.

Shall thy lovingkindness be declared in the grave?

Or thy faithfulness in destruction?

Shall thy wonders be known in the dark?

And thy righteousness in the land of forgetfulness?

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