noun

• (chiefly Western, often derogatory, colloquial) Any left-wing ideology, government regulations, or policies promoting a welfare state, nationalisation, etc.
  "This tax plan is communism!"
• (rare) Readiness to share scientific findings (the first of the Mertonian norms).
  "A recent survey of 633 South Korean scientists found not only that communism was the Mertonian norm they thought most respected in practice (Kim and Kim 2018, 9), but also that younger scientists’ replies showed evidence of ‘mounting tension between the commercialisation of academic science and the norm of communalism’ (Kim and Kim 2018, 19). Our focus on scientific communism and its relationship to commercial research may thus reflect the concerns of working scientists."
• (rare) communality, sharedness.
  "Rational expectations econometrics extends a communism of statistical models to include a “sharing with nature” that is an essential input into making maximum likelihood or generalized method of moments be good estimators."

noun

• (US, informal) A state of affairs perceived as oppressive, overly arbitrary, or totalitarian.
  "...he shouldn't...just...[say]..."I -- I am responsible for prosperity,"...that's Communism, Sir, you see."