Strangulation is killing someone by pressing on their throat so they cannot breathe — or the fact of dying that way. It is the formal noun, the one used by police, doctors, courts and news reports: 'death by strangulation', 'the post-mortem showed strangulation'. In ordinary talk people use the verb instead — 'he was strangled' — so if you are describing a crime in conversation, the verb is the natural choice and the noun sounds like a report. Doctors use it in a second, quite different way, for a body part whose blood supply is cut off by being squeezed: a strangulated hernia is a serious emergency because that piece of bowel is being throttled and will die. And it turns up as a metaphor for choking something non-living — 'the strangulation of free speech', 'the slow strangulation of small businesses by rules' — meaning something is being squeezed until it cannot function. The word is heavy in every use; it is never light or casual.