🔼The name Meah in the Bible
The name Meah (or rather: Hammeah, spelled המאה) occurs twice in the Bible, both times in the Book of Nehemiah. It's the name of a tower that was associated with the wall of Jerusalem. It was fully named Migdol Hammeah (מגדל המאה), and was restored by the high priest Eliashib and company (Nehemiah 3:1). This tower is mentioned again in the descriptions of the dedication ceremony, as one of the landmarks via which the second choir reached the restored temple of YHWH (Nehemiah 12:39).
For some reason, the NAS and NIV versions of the Bible insist on translating this name (as Tower of the Hundred). The JSP version speaks of the tower of Hammeah, due to the letter ה (he) prefixed to the meah-part. This prefix is very common in names of the format X-of-Y and is usually not transliterated as part of the actual name.
🔼Etymology of the name Meah
The name Meah is the same as the word מאה (me'a), which indicates an order of magnitude of roughly a hundred:
The name Meah means Hundred, but it's not clear why it was named such. Perhaps because it was a hundred cubits high or as far removed from a gate or the temple or even the other named tower, namely the tower of Hananel.
Some scholars even propose that the tower of Meah and the tower of Hananel were the same one (see Jeremiah 31:38) and that the name Meah referred to the many sheep that were brought in via the Sheep Gate and were awaiting sacrifice near the tower of Meah.
The bottom line is, however, that it's not known with any degree of certainty why this tower was called such.