 Lexical stress is a suprasegmental phonological phenomenon of present-day English, where the position of stress in polysyllabic words can serve to distinguish them. For example, the orthographically different words INSIGHT and INSIGHT are segmentally identical and are distinguished in pronunciation only by the fact that the stress is placed on the first syllable in INSIGHT and on the second syllable IN to INSIGHT. In some cases, lexical stress leads to systematic differences. For example, in a group of primarily dyssyllabic words which have their origin in the Romance languages, the placement of stress helps to distinguish the word class. Words such as CONTRAST and OBJECT are nouns since their first syllable is stressed, and they become verbs if stress falls on their second syllable as in CONTRAST and OBJECT. Note that the segmental structure changes too. The vowel of the unstressed syllable in the verbs becomes the mid-central vowel schwa. In cases such as ENTRANCE and PRESENT, these segmental differences are more obvious when stress shifts to the second syllable and turns these nouns into verbs as in INTRANCE and PRESENT. So lexical stress may distinguish between different words, between different word classes, and between different meanings of the same word.