אַךְ

From the study of Isaiah 45:24

Range of meaning

It can affirm ("surely, indeed") or restrict ("only, nothing but"). Which sense applies depends on context.

Against the English

KJV's "surely" takes the affirming sense. BSB, ESV, NASB and WEB use "alone" or "only", the restricting sense. BSB combines both ("Surely… alone").

Used elsewhere in the period

The restricting sense appears in 45:14 ("only ['akh] in you is God, and there is no other"). That close parallel in the same chapter strongly supports "only" here.

From the study of Proverbs 21:5

Range of meaning

A particle that either restricts ('only, nothing but') or affirms ('surely, indeed'). Often both senses are felt together.

Against the English

KJV and YLT 'only'. WEB, ESV and NASB use forms of 'surely / certainly'. BSB and NIV fold the second ʾak into a comparison ('as surely as'), which changes two parallel statements into one statement measured against the other.

Used elsewhere in the period

The phrase ʾak-ləmaḥsôr ('only to lack') is a fixed phrase in Proverbs: 11:24 (one who holds back what is due), 14:23 (mere talk), 22:16 (one who oppresses the poor or gives to the rich), and here.

From the study of Psalm 39:5

Range of meaning

An emphasising and limiting particle: 'surely, indeed', and also 'only, nothing but'. It often opens a firm statement that runs against what one might expect.

Against the English

KJV/YLT 'verily/only'; BSB 'Truly'; WEB/ESV 'Surely'. No single English word holds both 'surely' and 'merely' at once.

Used elsewhere in the period

Psalm 39 uses it four times (vv. 5, 6 twice, 11). Psalm 62, also headed 'to/according to Jeduthun', uses it six times, together with hevel (62:9). This suggests a shared style or tradition between the two psalms.