mon·ster 
(mŏnstər)
(mŏnstər)n.
1.
a. An imaginary or legendary creature, such as a centaur or Harpy, that combines parts from various animal or human forms.
b. A creature having a strange or frightening appearance.
2. Archaic An organism that has structural defects or deformities.
3. Informal A very large animal, plant, or object.
4. One who inspires horror or disgust: a monster of selfishness.
adj.
Informal Extremely large; monstrous: a monster hit at the box office; ate a monster steak.
[Middle English monstre, from Old French, from Latin mōnstrum, portent, monster, from monēre, to warn; see men-1 in the Appendix of Indo-European roots.]