hollow place, mortar

Boyd’s Bible Dictionary:

(1) Hollow vessel of wood or stone, in which corn was ground with a pestle (Num. 11:8; Prov. 27:22). (2) Various cementing substances used in building, as bitumen, clay, and ordinary mixture of sand and lime (Gen. 11:3; Ex. 1:14; Lev. 14:42; Isa. 41:25).

Concise Bible Dictionary:

Stone Mortar and Pestle
The monuments of Egypt show that anciently, as now, stone mortars with stone pestles were used for pounding hard seeds. The manna was ground in mills or beaten in a mortar (Num. 11:8). Though by this means the seeds were pounded very small, yet even such treatment would not cure a fool of his folly: it shows the incorrigible nature of him who despises wisdom and instruction (Prov. 27:22).

Strong’s Dictionary of Hebrew Words:

Transliteration:
maktesh
Phonic:
mak-taysh’
Meaning:
from 3806; a mortar; by analogy, a socket (of a tooth)
KJV Usage:
hollow place, mortar