shalal

Let's take a look at the word shalal שָׁלָל. It means "spoils, booty, plunder" and according to Klein, derives from the root שלל meaning "to spoil, to plunder, to deprive" and has the following origin:

Akka. shalālu, OSArab. תלל (= to plunder), and Arab. thalla (= flock of sheep or goats). cp. the related base נשׁל.]

The root נשל, in turn, means "to slip or drop off; to draw off."

Klein writes that this original root of שלל developed into two more meanings. One is found only once in the Bible:

שׁלל ᴵᴵ to draw out (sheaves).
    — Qal - שָׁלַל he drew out sheaves (a hapax legomenon in the Bible, occurring Ruth 2:16 in the phrase שֹׁל־תָּשֹׁלוּ, ‘you shall draw out (from the bundles)’. [Arab. salla (= he pulled out, withdrew). A special sense development of שׁלל ᴵ. cp. the related base שׁלה ᴵᴵ.] 

 The root שלה - "to draw out" - gives us a number of familiar words:

• shilya שליה - "placenta" (drawn out of the womb)
• shilhey שלהי - "the latter part of, the end of" (literally going away, leaving)
• shaldag שלדג - "kingfisher". Klein presents this etymology: "Coined by H.N. Bialik (1873–1934) as the abbreviation of שׁוֹלֶה דָּגִים, ‘(the bird) that draws out fishes’, from שׁוֹלֶה, part. of שָׁלָה (= he drew out), and דָּג (= fish)." It is also the name of an elite unit in the Israeli army.

A third meaning of שלל is the one most frequently found in Modern Hebrew. Klein suggests these meanings: "to remove; to refuse, to negate, to deny." When an army took the spoils, they "removed" them from those they defeated. So today when we use the verb shalal it generally means someone "rejected, denounced, ruled out" or "negated, refuted, disproved." From here we get the related words shelila שלילה - "rejection, invalidation, elimination" and shelili שלילי - "negative."

Another form of that verb is hishtolel השתולל. Today it means "to misbehave, to act unruly", but it originally meant "to be deranged", and Ben Yehuda indicates it therefore meant "to be lacking sanity."

One word that does not seem to fit this pattern is shelal שלל - "abundance". Klein says that this post-Biblical word (he defines as "bunch") actually comes from an unrelated homonym of שלל. This root means "to stitch loosely, join together loosely, to chain, fetter." He provides two possible etymologies:

Prob. denominated from שַׁלְשֶׁלֶת (= chain). However, it is also possible that שׁלל in this sense is a Shaph‘el verb formed from לוּלָאָה (= loop), so that שׁלל ᴵⱽ would properly mean ‘to tie with loops’.

Based on this meaning of the root, he writes that shelal was originally from the phrase shelal shel beitzim שלל של ביצים - "embryonic eggs joined together."

However, Even Shoshan says that shelal too originates in the meaning of "spoils". A victor reviewing his spoils would find a bounty before him, as in the metaphor found in Tehilim 119:162:

שָׂשׂ אָנֹכִי עַל־אִמְרָתֶךָ כְּמוֹצֵא שָׁלָל רָב׃
I rejoice over Your word as one who finds great spoil. 

An example of this sense development is found in the Song of Devorah (Shoftim 5:30):

הֲלֹא יִמְצְאוּ יְחַלְּקוּ שָׁלָל רַחַם רַחֲמָתַיִם לְרֹאשׁ גֶּבֶר שְׁלַל צְבָעִים לְסִיסְרָא שְׁלַל צְבָעִים רִקְמָה צֶבַע רִקְמָתַיִם לְצַוְּארֵי שָׁלָל׃
“They must be dividing the spoil they have found: A damsel or two for each man, Spoil of dyed cloths for Sisera, Spoil of embroidered cloths, A couple of embroidered cloths Round every neck as spoil.” 

Shelal tzevaim - "a spoil of color(ed cloths)" took on the sense of "an abundance (or variety) of colors."

So now we can see how one root developed into both very negative and very positive connotations.