1. imaginary number (mathematics) a number of the form a+bi where a and b are real numbers and i is the square root of -1
  2. imagery the ability to form mental pictures of things or events
  3. pure imaginary number an imaginary number of the form a+bi where a is 0
  4. imaginary place a place that exists only in imagination
  5. imaginary part the part of a complex number that has the square root of -1 as a factor
  6. ignorance the lack of knowledge or education
  7. ignorant uneducated in general; lacking knowledge or sophistication
  8. imagination image a mental image produced by the imagination
  9. Avogadro number the number of molecules in a mole of a substance
  10. irrational number a real number that cannot be expressed as a rational number
  11. imaginary being a creature of the imagination
  12. magic number the atomic number of an extra stable strongly bound atomic nucleus: 2, 8, 20, 28, 50, 82 or 126
  13. imaginary creature a creature of the imagination
  14. imaginary not based on fact; unreal
  15. ordinal number the number designating place in an ordered sequence
  16. imagination the ability to form mental pictures of things or events
  17. ignorantness ignorance (especially of orthodox beliefs)
  18. imaginativeness the formation of a mental image of something that is not perceived as real and is not present to the senses
  19. atomic number quantity of protons in the nucleus of an atom of an element
  20. imaginative comparison the kind of mental comparison that is expressed in similes or metaphors or allegories