faint: dimmed or faded, with the brightness, color, or strength nearly gone out of it.
Behind every use of this word is one picture: something that used to have brightness or strength in it and now has almost none.
- A skin mark that was a vivid white has gone dull.
- An old man's eyes have clouded over until he cannot see.
- A lamp wick is down to its last glow.
- A grieving person has no life left in him.
Hebrew describes all four with the same word, because the same thing is happening in each: whatever was bright in it is going out.
That is why the word is welcome news in Leviticus and grim news in Isaiah. When a priest inspected a skin condition, a bright mark that kept spreading kept a person shut away, while a mark that had faded and stayed put meant the trouble was passing and the person could be declared clean. Fading is what recovery looked like. In Isaiah the same fading describes a life that is nearly over.
Isaiah 42:3 is where the word became famous. The servant of the Lord will not break a bruised reed or put out a wick that is barely alight, a line Matthew 12:20 applies to Jesus. The force of it rests on this word: the flame is so far gone that anyone else would pinch it out and start fresh, and he will not.
The verb this word comes from (כָּהָה) covers the same ground, so the two often stand close together: a mark that has faded in Leviticus 13:6, Isaac's eyes growing dim in Genesis 27:1, everyone's spirit failing in Ezekiel 21:7, and, one verse after the wick, the promise that the servant himself will not grow faint in Isaiah 42:4.