to learn or teach: to transmit knowledge, skill, or conduct through instruction and practice
The word describes the two sides of a single act of passing something on. When the learner is in view, it means acquiring knowledge, a skill, or a pattern of conduct, through hearing Torah read, through watching a model, or through repeated practice. When the teacher is in view, it means causing that learning: imparting law, song, warfare, or custom to another person.
Dictionaries list this word under two glosses, "teach" and "learn," but these are not two separate words. They are the same word used two ways, one shape for the learner and another for the teacher, just as you would expect for a verb that describes a state. HALOT, BDB, and DCH all treat it as one root. The two activities, learning and teaching, share a single core: the deliberate passing of something from one person to another.
A third shade emerges in another form of the verb: being trained or habituated through repeated conditioning. Hosea 10:11 calls Ephraim "a trained heifer that loves to thresh", accustomed to the work, shaped by practice. Jeremiah 31:18 uses the same form for a calf "unaccustomed" (not yet trained). Isaiah 29:13 applies it to worship taught as a merely human precept. Here the word shades toward habit and disposition rather than active study, though the same idea of passing something on underlies it.
The word appears across Deuteronomy, the Psalms, and the Prophets. Deuteronomy's great concern is that Israel learn Torah, hear it, fear God, do it, and that parents and leaders teach it to the next generation. The Psalms repeatedly use the command form, asking God to teach the psalmist his statutes. The Prophets describe Israel learning wrong conduct: learning the ways of the nations (Jeremiah 10:2), teaching the tongue to lie (Jeremiah 9:5), training daughters to lament (Jeremiah 9:20).