tension
noun
ˈtenʃn 
ˈtenʃn 
1 [uncountable, countable, usually plural] tension (between A and B) a situation in which people do not trust each other, or feel unfriendly towards each other, and which may cause them to attack each otherThere is mounting tension along the border.international/racial/political tensionsFamily tensions and conflicts may lead to violence.The incident has further increased tension between the two countries.2 [countable, uncountable] tension (between A and B) a situation in which the fact that there are different needs or interests causes difficultiesThere is often a tension between the aims of the company and the wishes of the employees.3 [uncountable] a feeling of anxiety and stress that makes it impossible to relaxnervous tensionWe laughed and that helped ease the tension.Walking and swimming are excellent for releasing tension.a tension headache4 [uncountable] the feeling of fear and excitement that is created by a writer or a film/movie directordramatic tensionAs the movie progresses the tension builds.5 [uncountable] the state of being stretched tight; the extent to which something is stretched tightmuscular tensionAdjust the string tension of your tennis racket to suit your style of playing.When knitting, try to keep the same tension throughout.Massage can relieve tension in your shoulders and back. see also surface tension
Usage note: pressurestress tension strainThese are all words for the feelings of anxiety caused by the problems in somebody's life.pressure difficulties and feelings of anxiety that are caused by the need to achieve something or to behave in a particular way: She was unable to attend because of the pressures of work.stress pressure or anxiety caused by the problems in somebody's life: stress-related illnessespressure or stress?It is common to say that somebody is suffering from stress, while pressure may be the thing that causes stress.tension a feeling of anxiety and stress that makes it impossible to relax: nervous tensionstrain pressure on somebody/something because they have too much to do or manage; the problems, worry or anxiety that this produces: I found it a strain looking after four children.to be under pressure/stress/strainconsiderable pressure/stress/tension/strainto cause stress/tension/strainto cope with the pressure/stress/tension/strainto relieve/release the pressure/stress/tension/strainto be suffering from stress/tension