All languages have prosodic (supersegmental) systems that encompass different ways of giving prominence to certain syllables in the word via stress (loudness), pitch (high or low), or length (long or short). English is a stress language, in which the position of stress is mobile and can fall on any syllable (unlike, for instance, Czech, which has fixed stress on the initial syllable; or French, with stress on the final syllable). Occasionally word classes in English can be differentiated solely by stress, as in noun/verb pairs like pérmit/permít, cómbat/combát, etc.

Stress is also used to give emphasis to words. This can be accomplished by increasing the loudness of the stressed syllable beyond its normal degree; or by stressing syllables that are normally unstressed or bear secondary rather than primary stress.

Emphatic stress of the latter sort in particular can be called “hypermetrical” (adopting the term from verse analysis), by which is meant a stress on a syllable over and above the normal distribution. This is evidently what has happened in the recent history of American English as regards certain adverbs in {-ly} such as apparently, supposedly, etc., wherein some speakers are putting a hypermetrical stress on the final syllable for emphasis in addition to the normal primary stress on a medial syllable.