To taber means to beat a timbrel or drum, and in Nahum it describes the mourning attendants who beat their breasts in grief. Such beating expressed intense sorrow.
Definition
To taber means to beat a timbrel or drum. In the cited passage it describes beating the breast violently as an expression of mourning.
Biblical Usage
The word appears in the account of Nineveh’s capture, where a mourning retinue follows the dishonored queen or personified city. Beating the breast signifies intense grief.
Historical Bible Dictionaries
International Standard Bible Encyclopedia (ISBE)
<p>ta'-ber (taphaph, "to strike a timbrel" ((Ps 68:25)): The word is used only once in the King James Version, namely, in the exceedingly graphic account of the capture of Nineveh given in Na 2:7. The queen (perhaps the city personified) is dishonored and led into ignominious captivity, followed by a mourning retinue of "maids of honor" who taber upon, that is, beat violently, their breasts. Such drumming on the breasts was a gesture indicative of great grief (Lu 18:3).</p>