Measurements: ‘marked’ and ‘unmarked’ forms

Many adjectives that are used in measurements come in pairs (e.g. tall/short, old/young, heavy/light, fast/slow). The word that is used for the ‘top’ end of the measurement scale can usually be used in another sense, to talk about the quality in general. For instance, one can ask how long something is even if it is relatively short. Grammarians call these uses ‘unmarked’. Compare:

• She’s very tall and he’s very short. (marked)
  Exactly how tall are they both? (unmarked) (not Exactly how short …)
• Will you still love me when I’m old? (marked)
  He’s only twenty-three years old. (unmarked) (not … years young.)
• Lead is one of the heaviest metals. (marked)
  Scales measure how heavy things are. (unmarked) (not … how light …)

Some nouns are used in similar ‘unmarked’ ways. Compare:

• Age brings wisdom but I’d rather have youth and stupidity. (marked)
  What is her exact age? (unmarked) (not What is her exact youth?)
• The worst thing about the film was its length. (marked)
  What’s the length of the runway? (unmarked) (not What’s the shortness …?)