adj

• (art, music, literature) Preferring redundancy; tending to do or provide more rather than less.
  "This, his [Frank Stella's] second Museum of Modern Art retrospective, shows him in his second incarnation, turning his back on Minimalist rationality and opting for a “maximalist,” seemingly free-wheeling Baroque complexity that helped set the stage for New-Expressionism."
• (politics, diplomacy) Aggressive, expansive.
  "Mr. Schmidt agreed that “both the Russians and the Americans want results,” but he warned that they have a long way to go from “maximalist” starting positions."
• (religion, Christianity) Relating to religious or Biblical maximalism.
  "Again, the progressive view was that the Mother of Jesus should receive all veneration for holiness, but not the title of mediator between God and man. Much of the Curia supported a “maximalist” cult of the Virgin."
• (historical, communism) Relating to far-left communism.
  "His inclusion in the official delegation to Moscow caused surprise today and was seen as indicative of the Italian Communists' aversion to Maximalist currents in international communism."

noun

• (art, literature, music) A person with maximalist beliefs or tendencies; someone who prefers redundancy or excess, especially in the arts.
  "Concerning his own purpose in making music, Mr. Babbitt says he would call himself a maximalist: “I try to make music as much as it has ever been or as much as it could be. I may try to put too much into a piece. […]”"
• (politics) A supporter of an aggressive or expansive foreign policy.
  "But on the larger issues, the range of opinion on the best solution runs the gamut from the so‐called hawks, or “maximalists,” as they have come to be known, and the doves, or “minimalists.” The first group would have Israel keep most of the Arab territory she now occupies, and would postpone any significant action on the Palestinian claims until after an over‐all peace agreement was reached with the Arab states."
• (religion) A proponent of Biblical maximalism, one who affirms the historicity of central Biblical narratives.
  "The first is reported to represent the secretariat's attempted compromise between the “maximalists” and those who see the further aggrandizement of the cult of Mary as a further obstacle to a dialogue with the Protestants."
• (historical, communism, obsolete, capitalized) A Bolshevik.
  "After a firm opening and an hour of fairly well sustained strength the stock market once more suffered a wide break yesterday following the receipt of the news of the overthrow of Kerensky and the announced intention of the Maximalists to propose an immediate peace with Germany."