means The accumulated body of knowledge, traditions, and stories about a subject, passed down informally rather than through official instruction.

from From Old English 'lar,' meaning teaching, learning, or instruction — a close relative of the verb 'learn' and the German 'Lehre' (doctrine, teaching). For centuries it simply meant what you were taught; only later did it drift toward the unofficial, hand-me-down knowledge of folklore, myth, and craft — the wisdom you absorb rather than the kind you're examined on.