c. 1600, "tearful," from Middle English fem. proper name Maudelen (early 14c.), from Magdalene (Old French Madelaine), woman's name, originally surname of Mary the repentant sinner forgiven by Jesus in Luke vii:37. In paintings, she often was shown weeping as a sign of repentance. Meaning "characterized by tearful sentimentality" is recorded by 1630sAnd here is their entry for Magdalene:
fem. proper name, from Latin (Maria) Magdalena, from Greek Magdalene, literally "woman of Magdala," from Aramaic Maghdela, place on the Sea of Galilee, literally "tower."
Magdala was the name of a number of places in the Second Temple period (mentioned in both Jewish and Christian sources.) Later an Arab village, al-Majdal, preserved the name of Magdala, and in 1910, once again a Jewish town, in the same area, took up the name - Migdal.
The Aramaic Maghdela is cognate with the Hebrew migdal מגדל - "tower", and derives from the root גדל, meaning "great, large, tall", as in the word gadol גדול - "big". There is another meaning of גדל - "twist, plait", and from here we get the synonym for tzitzit - gedilim גדילים in Devarim 22:12. Klein says they might be related, since twisting a cord makes it strong, i.e. great.
A different theory, mentioned in this entry in the Theological Dictionary of the Old Testament, says that the two meanings of גדל are not related, and in fact, suggests that migdal actually derives from degel דגל (originally meaning "to look"):
The natural identification of the word migdal as a miqtal construction from a root gdl is problematical because only Canaanite attests the root gdl in the meaning "be large, high" (cf. in contrast Arab. gadala, "twist or pull tightly, plait"), and because the context of several OT occurences (e..g Isa 5:2) does not suggest something large and high. Thus there is some reason to follow the suggest first articulated by William F. Albright that the word migdal arose through metathesis from midgal (cf. Akk. madgaltu, "watchtower, border post").
The same entry mentions that the word migdal (or migdol) was so frequent in place names in the region, that Herodotus (Histories 2:159) mistakenly describes the famous biblical Battle of Megiddo as taking place in Magdolus. The Christian Book of Revelation describes a future battle to take place at Har Megiddo - which in Greek became Armageddon. Eventually, Armageddon took on the meaning of "a final conflict" or "the end of the world."
Zev Vilnay writes here that the place name Megiddo מגידו likely has the following origin: מגדו — מקום גדודים - "Megido - a place of troops (gedudim)". Others connect it to the word meged מגד - "bounty" (of food).
So from the sad maudlin and the scary Armageddon, if we dig a little further, we find greatness and bounty. The optimism of etymology!