The name of the tree in question, in Hebrew, is Eytz haDa’ath Tov v’Ra’ (עצ הדעת טוב ורע), with da’ath being the word for knowledge (Strongs #1847). Da’ath is actually a fairly common word, appearing 92 times in the Tanakh. Of those 92 times, it is translated “knowledge” 81 times in the NASB and 80 times in the KJV. Of the other uses of the word (going from the NASB, which is easier to search for hits with my current tools), it is used to mean concern (1), know (3), premeditation/ intentionally (4), skill (1), truth (1), what (1). Of the four times it refers to premeditation or intentionally, two are with a negative participle (that is, “unintentionally”).
In all cases, the word simply refers to conscious knowledge of a matter. If you are interested in Hebrew root words, the root of da’ath is da’ (דע), which literally means “door of the eye”—the eyes being the principle way in which humans gain knowledge about the world. The equivalent Greek word, used in the Septuagint translation, is gnooston (γνωστον, Strongs #1110), from gnosis, or knowledge. Lest anyone try to draw a connection between that and Gnosticism, I should point out that the word has no negative context in and of itself, appearing in various conjugations 15 times in the NT to mean simply something known.
Indeed, the Scriptures are overwhelmingly positive about Man having da’ath, particularly in the Proverbs. It is often paired with the ideas of wisdom (cf. Exo. 31:3, Ecc. 7:12) and self-discipline (Pro. 12:1 and 17:27). Outside of the narrative of the Fall, the worse the Bible has to say of it is that an increase of knowledge can bring one pain (Ecc. 1:18)—of course, given the genre of Ecclesiastes, perhaps we should consider that to mean knowledge outside of the Eternal One’s.
I’ve given you the Strong’s numbers so that you can double-check my research. However, I have to say that “knowledge” really is the best translation of the idea of da’ath. Given the overwhelmingly positive view the Bible takes of real knowledge, I would suggest that if anything, we can understand this passage to teach that the knowledge of good and evil were not sinful per se, but rather that the avenue that Adam and Havah took (disobedience to the Father’s clear command) in pursuit of this knowledge is the reason behind the Fall.
In other words, the ends—however noble—do not justify the means of disobeying ADONAI.Shalom!