Abarim Publications' online Biblical Hebrew Dictionary
The verb בצל (bsl) doesn't occur in the Hebrew of the Bible, but it occurs in cognate languages where it means to strip or strip off. This root's sole Biblical derivation is the masculine noun בצל (basal), possibly meaning onion but perhaps more generally denoting flower bulbs and buds. This word occurs only in Numbers 11:5.
The word חבצלת (habasilat) occurs only twice in the Bible, in Song of Solomon 2:1 (the "rose" of Sharon) and Isaiah 35:1 (here commonly translated as "crocus"). This word probably described some sort of meadow saffron or autumn crocus, but more to the point referred to a plant's bulb or flower buds.
Both Gesenius and Marcus Jastrow (Dictionary of the Targumim, Talmud Bavli, Talmud Yerushalmi and Midrashic Literature) declare that our word חבצלת (habasilat) is basically an expanded version of בצל (basal), and Jastrow surmises additionally that our word begins with an expression of the verb חבב (habab), to love.
Here at Abarim Publications we suspect that these words ultimately may have helped the formation of the turban to signify, well, budding intellects, or at least philosophers, i.e. lovers of wisdom.
The Biblical word for science or scientific knowledge is דבר (dabar), from which comes the word דברה (debora) or honey bee, which explains the link to flowers. Ultimately, these words may have inspired the naming of basil, the proverbial "royal herb", from the Greek word βασιλευς (basileus), meaning king.
See our article on the name Habakkuk for more on this.