A stress-timed language is a language where the stressed syllables are said at approximately regular intervals, and unstressed syllables shorten to fit this rhythm. Stress-timed languages can be compared with syllable-timed ones, where each syllable takes roughly the same amount of time.
English and German are examples of stress-timed languages, while Spanish and Cantonese are syllable-timed.
In the classroom
Learners whose first language is syllable-timed often have problems producing the unstressed sounds in a stress-timed language like English, tending to give them equal stress.