Indeed, it is a source of common (i) __________ among engineers, who smirk that the average layman cannot differentiate between the man who runs a locomotive and the man who designs a locomotive. In ordinary (ii) __________, both are called engineers.To smirk is to smile in an irritating and smug fashion, therefore, the word for the first blank is
amusement.
Since, the engineers are amused by the fact that the average layman cannot differentiate between the man who runs a locomotive and one designs it, the second sentence should convey the sense of:
In ordinary language, both are called engineers.
Therefore, the word for the second blank is
parlance, which is a particular way of speaking or using words, especially a way common to those with a particular job or interest.
_________________