agonist
1. [ noun ] (biochemistry) a drug that can combine with a receptor on a cell to produce a physiological reaction
Related terms: drug biochemistry
2. [ noun ] someone involved in a contest or battle (as in an agon)
Related terms: adversary contestant
3. [ noun ] (writing) the principal character in a work of fiction
Synonyms: protagonist
Related terms: fictional_character antihero
4. [ noun ] (anatomy,zoology) a muscle that contracts while another relaxes
Examples:

"when bending the elbow the biceps are the agonist"

Related terms: antagonistic_muscle
Similar spelling:   agonistic
  agonise
  agonised
  Agnus
  agnostic
  Agnes
  agonising
  Agonus
  agnise
  agnostical
  agonize
  agnosia
  agenise
  Aguiniga
  agonized
  agenesis
  agenesia
  against
  agonizing
  Agnus_Dei
  aging