From tsalal; shade -- bottom.
see HEBREW tsalal
H4699. metsullah
מְצֻלָה noun feminine dubious word: Zechariah 1:8 the myrtles which are ׳בַּמּ, apparently some locality about Jerusalem, called the basin, hollow; GASm glen or valley-bottom; possibly is מְצֻלָּה, < מְצִלָּה, shadow (III. צלל).