The property that each named value reference in a macro expansion means the same thing as it meant at the place in the original source code from which it was copied into the macro expansion See "Hygiene" on page 161
of households and communities; a system of principles or rules designated for the promotion of health
Hygiene is the practice of keeping yourself and your surroundings clean, especially in order to prevent illness or the spread of diseases. Be extra careful about personal hygiene. = cleanliness. the practice of keeping yourself and the things around you clean in order to prevent diseases (hygène, from hygieina, from hygies )