gmalivuk wrote:"Rent" means both in English, "like" switched directions (it used to mean something like "please"), and "leornian" and "læran" were similar enough in Old English that "learn" came to acceptably mean both "receive knowledge" and "give knowledge" for about 600 years. (The verb "learn" sounds rustic as a synonym for "teach", but the participial adjective "learned" is still perfectly acceptable in standard English.)
In German learn is lernen and teach is lehren (or beibringen ... lehren is a different register and also usually means a formal teaching relationship), but younger school children, at least in the area I grew up in (Saxony), use "I will learn you" instead of "I will teach you" nearly 100% of the time.
There are also a number of words English treats as symmetrical which other languages don't. Learners sometimes have trouble with the fact that both "brother-in-law" and "sister-in-law" can mean both your sibling's spouse and your spouse's sibling.
Interesting. Which languages distinguish this? I would guess e.g. Chinese, where there are even different words for younger and older brother etc. But are there e.g. Indoeuropean languages that do it, too?