【Emphasis】 , 【stress】 ,  【accent】 ,  【accentuation】  denote exerted force by which one thing stands out conspicuously among other things; they also often designate the effect produced or the means used in gaining this effect.

【Emphasis】 implies effort to bring out what is significant or important. Sometimes it also suggests vigor or intensity of feeling.

【Stress】 , though often used interchangeably with  【emphasis】 , is distinguishable from it both in some of its implications and in its association with particular arts, where it has acquired specific meanings. It rarely loses entirely its original implication of weight that causes pressure or strain, though this is often merely suggested.

At times  【stress】 strongly implies urgency or insistency.

In phonetics and prosody  【stress】 is the general term referring to the prominence given to certain syllables by force of utterance. It may also be used of the natural 【emphasis】 on certain words in a sentence. It may even suggest degree of 【emphasis】 .

【Accent】  implies contrast for the sake of effect, very frequently an aesthetic effect.  【Accent】 carries no connotation of weight, but it strongly suggests relief in both senses, that of relieving monotony and that of bringing out sharply or into relief.

In prosody 【accent】 is the form of 【stress】 characteristic of English verse, akin to the beat in music and involving force in utterance. In English phonetics  【accent】  and  【stress】  are commonly used interchangeably. Since force of utterance ( 【stress】  ) is the principal means by which a syllable, a word, or a group of words is accented or brought into sharp contrast with the others, one may speak of syllabic  【accent】  or  【stress】 , or word  【accent】  or  【stress】 .

【Accentuation】 , though close to  【accent】 (except in technical senses), often goes beyond it in its 【emphasis】 on increased conspicuousness; it also often suggests disagreeableness in the contrast.