Fit as a Fiddle

Etymology:

• It is an old expression or idiom of early 17th century. We know “fit” always means to be “in excellent vigor” but in this simile it has been joined with the word “fiddle”. The reason might be the alliteration sounds both the words “fit” and “fiddle” give. So any fiddle that perfectly fits in something is considered well shaped and tuned because it not only fits well but also sounds well thus rightly to be called as “Fit as fiddle”.