Every polysyllabic word has one or more syllables of greater prominence than the others. Such syllables are said to be accented or stress. Sound loudness, pitch, sound quantity (length), or sound quality may render a syllable more prominent than the others.
Word stress performs two linguistic functions: constitutive (arranging syllables in words) and distinctive (differentiating the meaning of words consisting of the same morphemes).
Many polysyllabic English words have both primary and secondary types of stress. There is a group of words in English which have 2 equally strong stresses: ´re´write, ´four´teen. There are two main principles of marking word-stress:
1) the root syllable is stressed: ´clever, ´water, ´singing; be´fore, be´gin, mis´take.
2) the third syllable from the end is stressed: ar´ticulate, ´stimulate, ´situate.
According to both rules most disyllabic words have their stress on the first syllable: ´finish,´answer.
Disyllabic French borrowings have the primary stress on the last syllable: machine, police.
Words of 3 syllables generally have stress on the first syllable: ′cinema, ′afterwards, ′recognize.
Words with suffixes -ate, -fy, -ize usually have their stress on the third syllable from the end: ′qualify, ar′ticulate, ′centralize.
The secondary stress is manifested in polysyllabic words with the primary stressed on the third or the fourth syllable from the beginning: popu´larity, respon´sibility, deco´ration, experimen´tation, articu´lation.
If the original word has a primary stress on the first syllable, the derived word would have its stress (primary or secondary) there also: ´possible – possi´bility.