Abarim Publications' online Biblical Hebrew Dictionary
The verb ברז (baraz) is unused in the Old Testament, and we can't be sure what it might have meant (or even whether it actually existed in Hebrew), but in Aramaic it existed meaning to bore or pierce, and had possibly to do with a word meaning outside, prairie or even prostitute; all related to באר (be'er), pit, and בר (bar), field, from the broadly attested root ברר (barar), meaning to be clear or free. The reason why this mystery verb ברז (baraz) is mentioned at all in dictionaries is that it might have had to do with the important noun ברזל (barzel), meaning iron:
The masculine noun ברזל (barzel) means iron, and it's a mystery where it came from, and thus what iron literally meant to the ancients (unlike English, Hebrew words are commonly part of large families of similar words, and words that look alike commonly have similar meanings).
Older dictionaries commonly attach our noun ברזל (barzel) to the verb ברז (baraz), to pierce, on account that iron objects were commonly used to skewer things, but fail to explain where the final ל (lamed) might have come from (as this is not at all a common suffix), or why bronze wasn't called after ברז (baraz), since bronze was used to skewer things long before iron was.
More modern commentators confidently declare that the quadriliteral (four-letter) word ברזל (brzl), meaning iron, existed all over the Semitic language spectrum and appears to have originated in Hittite (as barzillu), or else a Phoenician dialect, but obviously, there's no way to tell what barzillu might have literally meant and thus what sentiment iron was named after. The Arabic firzil and even the familiar Latin ferrum all derive from our source word ברזל (brzl), but it remains utterly unclear what the first users of that word had meant to say with it.
However, words were extremely important to the Hebrews and language sat enthroned like a deity at the heart of Jewish society — quite literally; see our article on the name YHWH, the name of the Lord, which was probably the Hebrew way of saying ABC. Linguistic science was considered a very important part of worship and Hebrew linguists rarely did things for no reason. Iron ushered in a new age, and the Iron Age began around the same time that the alphabet was completed (Psalm 16:10), when mass literacy became the norm and every ordinary man began to have access to the recorded history and science that until then was the prerogative of highly specialized priests (Exodus 19:6). If these brilliant scholars indeed accepted the word ברזל (barzel) from a foreign language, and adopted it without altering it to their design (like they commonly did with famous names; see our article on Amraphel), it must have meant something fitting to them, in Hebrew.
Most Hebrew words consist of three letters, and words of two of four letters can often easily be derived from a triliteral root. Not so with ברזל (barzel), and that makes it likely that this word looked sufficiently enough like one or more meaningful compounds of multiple existing words. Or perhaps better formulated: our word ברזל (barzel) was accepted into the Hebrew vocabulary because, despite its irrelevant original meaning, it clearly declared what the ancient Hebrews thought of iron. The Iron Age started around the time of David (10th century BC) but by then, iron had been known about for thousands of years and iron smelting had been going on since the Middle Bronze Age (centuries before iron overtook bronze as the choice metal for tools and weapons). That means that iron had originally been rejected, and that the Iron Age began not when ancient engineers figured how to work it, but when their warnings began to be ignored.
The word ברזל (barzel) may have resembled a compound based on the verb רזה (raza), to grow thin or to waste away, and particularly the noun רזי (razi), a wasting away, combined with לי (le ay), to me, as used in Isaiah's (8th century BC) haunting cry: "From the ends of the earth we hear songs, "Glory to the Righteous One," But I say, "Woe to me! (רזי־לי, razi-lay) Woe to me! (רזי־לי, razi-lay); Alas for me! The treacherous deal treacherously, and the treacherous deal very treacherously"" (Isaiah 24:16). The leading ב (b) could be ascribed to the particle ב (be), meaning in. And the whole compound ברזל (barzel) could be construed as a compressed version of ברזי־לי, b'razi-lay, meaning "in [this is] the demise of [everyone]".
Another way to explain our noun ברזל (barzel) is as a compound of the adjective בר (bar), meaning pure or clean, from the root we mentioned earlier: ברר (barar), to be pure or clean. The second part could be construed to come from the verb זלל (zalal), which sometimes means to shake or agitate, but mostly means to be worthless or make light of (the related verb זול, zul, means to be cheap or of little value).
Psalm 12:6 reads: "The words of the Lord are pure words; As silver tried in a furnace on the earth, refined seven times." Psalm 12:8 reads: "The wicked strut about on every side, when worthlessness (from זלל, zalal) is exalted among the sons of men."