Abarim Publications' online Biblical Hebrew Dictionary
חשב
The verb חשב (hashab) means to think up: to contemplate or devise. This verb primarily speaks of newly creating something mentally — a plan (Jeremiah 48:2, Ezekiel 38:10), artistic designs (Exodus 31:4), music (Amos 6:5) — and when it's used in the sense of to esteem or to reckon certain qualities in people (Genesis 38:15, Isaiah 53:4, Job 41:19) or materials (Isaiah 13:17), the implication is that these qualities are fabricated by the viewer rather than objectively observed.
Of course, when the Creator himself "reckons" someone righteous, this reckoning ends up being more real than the original (Genesis 15:6). Likewise Malachi 3:16 speaks of men who "esteem" the name YHWH, which does not speak of devotion or fidelity in a religious sense, but rather the patiently expanding of the knowledge of creation by exercising logic and the scientific method.
The derivations of this verb are:
- The masculine noun חשב (hesheb), which exclusively describes an item or quality associated with the priestly ephod (Exodus 28:8, 28:27-28, 29:5, 39:5, 39:20-21, Leviticus 8:7). Most translations take this to be a "skillfully woven band" (NAS) or a "curious girdle" (KJV), but that's little more than a guess. It may very well have been something like a Rorschach inkblot.
- The masculine noun חשבון (heshbon), a thinking up, or a thing thought up. In the Bible this word appears to denote the entirety of synthetic knowledge, which thus probably refers to art and technology: "... adding one thing to another to find חשבון (heshbon)" (Proverbs 7:27). This word appears two more times in the Bible (Ecclesiastes 7:25, 9:10), coupled with wisdom (חכמה, hokma) and knowledge (דעת, da'at).
- The similar masculine noun חשבון (hishabon), meaning device. This noun is used only once, in plural, in Ecclesiastes 7:29. Note that the difference between this noun and the previous one depends solely on the Masoretic diacritics, which didn't exist for the first fifteen hundred years of the existence of Ecclesiastes.
- The feminine noun מחשבה (mahashaba) technically denotes agency of the verb — a doer, instrument, place or instance of חשב (hashab) — but in effect it comes down to a thought (Psalm 94:11, Micah 4:12), a devising (Psalm 56:5, Jeremiah 6:19), a plan (Proverbs 19:21, Job 21:27). The difference with any old thought an a מחשבה (mahashaba) is that the latter denotes actual mental reality; not mere musings but assessments that drive actions, and plans that demand executions. When Isaiah famously states that God's thoughts are higher than man's thoughts (Isaiah 55:8-9), he isn't talking about abstract theories but about DNA versus the iPhone and the galaxy versus a string of Christmas tree lights.