A French Phrase Similar to "Expertise"

I am looking for a phrase that is used occasionally in English as a near synonym of "expertise". For some reason, "coup d'mentarie" keeps going through my mind, but I don't believe this actually means anything at all and it doesn't produce any results on the web.

To clarify, I am looking for a word or phrase that sounds similar to this, whilst I am foggy about the language of origin and precise meaning. French is just a guess. :)

Solution 1:

Playing violin is George's forte

a person's strong suit, or most highly developed characteristic, talent, or skill;
something that one excels in.

Etymologically,

1640s, from French fort "strong point (of a sword blade)," also fort, from Middle French fort.
Meaning "strong point of a person" is from 1680s.
Final -e- added 18c. in imitation of Italian forte "strong."

So don't let anyone tell you it's "Italian". It's French.

Solution 2:

You might be looking for the phrase "savoir-faire" also.

In English, it mainly means know-how (knowing how to do) but it connotes a knowledge that comes from an expertise as well.

From vocabulary.com:

The nearest English equivalent of savoir-faire is know-how. But while know-how pertains to nearly all skills, especially practical ones, savoir-faire usually refers specifically to skill in social and diplomatic situations.

Reference to expertise makes more sense in French though.

From the book "Knowledge, Skills and Competence in the European Labour Market" By Michaela Brockmann, Linda Clarke, Christopher Winch:

"Savoir-faire" based on the implementation in a concrete situation of both knowledge and experience (such as the blue-collar worker's manual dexterity, the skilled woker's ability to deal with breakdowns or malfunctions). This 'empirical' "savoir-faire" may be acquire both through leanring and through professional practice.