Meaning and pronunciation of יישר כחך

Question

What is the exact meaning of the phrase "יישר כחך", and what is the gramatically-correct way to pronounce it?

Answer 1

The expression is taken from the Talumd (Shabbat 87a and several other locations). The sage Resh Lakish expands the word "אשר" to the now ubiquitous "ישר כחך" .

You can see from the following Talmudic excerpt (Shabbat 87a) that the original use was to validate Moshe Rabeinu's action. It would seem to me that current usage is quite the same. When one performs a Mitzvah those around him will confirm that the action was proper and worthy of validation and strengthening (the action or possibly the performer.)

For it was taught, Three things did Moses do of his own understanding, and the Holy One, blessed be He, gave His approval: he added one day of his own understanding, he separated himself from his wife, and he broke the Tables. ... 'He broke the Tables': ... And how do we know that the Holy One, blessed be He, gave His approval? Because it is said, which thou brakest, and Resh Lakish interpreted this: All strength to thee (=יישר כחך) that thou brakest it.

What a great question! Shkoiyech!

Answer 2

Literally it means "He (i.e. Hashem) should straighten your energy." It means that Hashem should guide you in choosing actions that will allow your energy to flow on a straight path from its source on high down to you.

It is correctly pronounced "Yi/Ya/sher Ko/cha/cha". Its Yiddish pronunciation is "Ya/shi/koi/yach".