Abarim Publications' online Biblical Hebrew Dictionary
מחה מחח מחא
Scholars identify two separate roots מחה (maha), which appear to be not all that dissimilar, and one of which is related to the verb מחא (maha'). And then there is a root מחח (mhh), which yields the verb מחה (maha), which is spelled and pronounced exactly like the previous two:
מחה I
The verb מחה (maha I) means to wipe. It's used for wiping the mouth (Proverbs 30:20), tears from the face (Isaiah 25:8), or a city like a dish (2 Kings 21:13). Following the latter usage, this verb is also used to denote a wiping or blotting out: Moses' name from God's book (Exodus 32:32), a memory (Deuteronomy 9:14), or all living things (Genesis 7:23).
There are no derivatives to this verb.
מחה II
The identical verb מחה (maha II) means to strike and is used only once, in Numbers 34:11. This verb has one derivative: the masculine noun מחי (mehi), meaning stroke. This noun is used only once as well, in Ezekiel 26:9.
מחא
The verb מחא (maha') appears to be the same as מחה (maha II), except that it follows the Aramaic spelling, and it's only used to mean to clap, as expression of joy. It occurs three times in the Bible, in Psalm 98:8, Isaiah 55:12 and Ezekiel 25:6.
מחח
The root מחח (mhh) isn't used as verb in the Bible, but in Arabic it means to be fat or contain marrow. The Bible does contain three derivations of this root:
- The masculine noun מח (meah), meaning fatling. This word occurs twice, in Psalm 66:15 and Isaiah 5:17.
- The masculine noun מח (moah), meaning marrow (Job 21:24 only).
- The denominative verb מחה (maha), meaning to be marrow-filled or marrowy. This verb is formed after the noun moah meaning marrow, but it is spelled and pronounced identical to the verbs מחה (maha I and II).