Be Weak - Vine's Expository Dictionary of Old Testament Words
Usage Number: 1
Strong's Number: H3782
Original Word: kashal
Usage Notes: "to stumble, stagger, totter, be thrown down." As in biblical Hebrew, this word is used in modern Hebrew in the sense of "to stumble, fail." It occurs in the text of the Hebrew Old Testament approximately 60 times, the first time being in Lev. 26:37: "And they shall fall one upon another…." This use illustrates the basic idea that one "stumbles" because of something or over something. Heavy physical burdens cause one "to stagger": "… The children fell under the [loads of] wood" (Lam. 5:13).
This word is often used figuratively to describe the consequences of divine judgment on sin: "Behold, I will lay stumbling blocks before this people, and the fathers and the sons together shall fall upon them …" (Jer. 6:21). Babylon, too, will know God's judgment: "And the most proud shall stumble and fall …" (Jer. 50:32). When the psalmist says: "My knees totter from my fasting" (Psa. 109:24, nab), he means: "My knees are weak" (as translated by kjv, nasb, rsv, jb, neb, tev).