Abarim Publications' online Biblical Hebrew Dictionary
There are two roots of the form צלע (sl'), or so it is assumed. In Latin exists an almost identical duality in the verb(s) claudo; one means to limp and the other means to shut or shut in something that is open.
The root צלע (sl' I) isn't used as verb in the Bible, so we don't know what it might have meant (that is, of course, if we insists that it's not the same as צלע, sl' II, treated below). Its only extant derivation is the (mostly) feminine noun צלע (sela'), and that noun is problematic too.
Dictionaries will state that this noun most basically means side, and from there it may denote a man's rib (Adam's Eve-producing rib; Genesis 2:21), the "ribs" of a building structure (1 Kings 6:15), and even side-chambers, which BDB helpfully explains as "enclosing the temple like ribs". Once it seems to denote the "rib" (that is: a ridge) of a hill (2 Samuel 16:13), and once the leaves of a door (1 Kings 6:34).
Here at Abarim Publications we whole-heartedly disagree with these interpretations. We also disagree with the assumption that we're dealing with two different roots. In fact, we are pretty sure that there is only one root, which means to lean upon, and more specifically: to lean upon sideways (like someone limping).
The "rib" of the hill along which the disgruntled Shimei followed David was not a ridge but an overhanging bluff from which Shimei could conveniently pelt David with stones and dust (2 Samuel 16:13). The temple's walls and floor did not have "ribs," but supports upon which the whole building leaned (1 Kings 6:15-16). In 1 Kings 6:34 we read that the stud beams upon which the temple doors leaned were cylindrical supports (and not folding leaves, as tradition dictates; see our article on the word גליל, galil, meaning support and not folding).
The side-rooms of the temple were not like ribs enclosing the main temple like a rib cage (BDB boldly forwards this simile, which is in all honesty rather daft). The "side rooms" of the temple weren't side rooms and certainly not ribs. They were buttresses, like the side-aisles of a medieval cathedral; they kept the walls of the main building from bulging outward (1 Kings 6:5-6, 7:3, Ezekiel 41:5). The carrier rings of the Ark of the Covenant and the bronze altar weren't simply attached to the "sides" of these items but to their vertical structural supports (Exodus 25:12, 27:7). The same goes for the "sides" of the tabernacle itself, to which the boards were attached (Exodus 26:20).
But obviously, the idea that our word must mean rib comes from the old legend that YHWH formed mankind's first woman Eve out of a rib that he had removed from mankind's first man Adam's rib cage (Genesis 2:21). That, we know now, never happened.
The story of Adam and Eve is not about two naked people in a garden, but about the very first living things from which the entire biosphere was formed (to give a hint: Eve was the mother of all living, not just the humans; see for a closer look at this our articles on the phrase "all life" and on the Chaotic Set Theory). In short: Adam represents a living individual and Eve represents the interconnected biosphere. As Genesis clearly explains, Eve cannot exist without Adam; the living biosphere is formed from the co-dependency and inter-dependency of living individuals. The becoming of "one flesh" as stated in Genesis 2:24 is of similar gist as the report that the Lord "closed up the flesh" of Adam as he took hold and directed the leanings of Adam (Genesis 2:21).
The "other" root צלע (sl' II) does occur as verb in the Bible (this verb is obviously the parent of the noun צלע, sela', treated above) and means to limp or stumble, or rather: to walk while having a need to lean on something. It occurs a mere three times: Jacob was leaning on his ירך (yarek) after his encounter with the angel (Genesis 32:31). In the last days, YHWH will gather the leaners/limpers (Micah 4:6-7), and YHWH will save the leaners/limpers (Zephaniah 3:19).
This verb has one derivative (not counting צלע, sela'), and that is the nearly identical masculine noun צלע (sela'), meaning a limping/leaning, and this noun too occurs a mere three times in the Bible:
The prophet Jeremiah didn't simply note that his previously trusted but now corrupted friends waited for his "fall"; they were keeping an eye on what he leaned on (Jeremiah 20:10). Job's erring friend Bildad said something similar about the wicked, whose strength is famished and calamity is in what he leans on (Job 18:12). And David reflected that when his foot slipped, those who sought to injure him would magnify themselves against him because he was ready to stumble and grab hold of them for support (Psalm 38:17).
Another word that is often thought to mean lame or cripple is פסח (piseah), which is related to or the same as פסח (pesah), Pesah or Passover.