Literal Translation
At the flower of the skin?!
Actual Meaning
To be very sensitive, touchy, on edge
Etymology
The word ‘flower’ in this expression comes from the Latin “florem”. It has another meaning, which refers to ‘the best part of something’. This is where the expression ‘à fleur de’ comes from, meaning ‘on the surface of’.
It’s also understandable when thinking about the effect that the slightest touch can cause between lovers, but in this case it’s the negative sense of that light touch that produces an immediate reaction. It is by analogy with this situation that we say that a person has a sensitivity ‘à fleur de peau’ (on edge). In other words, they are likely to react brutally to what they may perceive as an aggression.