Partial - impartial

The adjective partial is used in two broadly different ways. Both are derived from the noun part. The negative form impartial is only used as the opposite of one of these.

• Partial in one usage means 'only a part of [a whole]'. Sometimes it is specifically opposed to 'total', as in astronomy, where a partial eclipse and a total eclipse are significantly different. Partial has other technical applications in various academic subjects, notably Maths.
• The second strand of meaning of partial is 'favouring one side over another', 'biased' or 'prejudiced towards one side of an argument'. (This is derived from 'part' in the sense of 'a faction': a similar use of language gave us the word '[political] party'.)
  • More colloquially, the phrase 'I'm very partial to [a food or a drink]' means 'I like it a lot'.
• The negative impartial is only used to mean 'unbiased' or 'disinterested'. The best opposites for the sense of partial that means 'bitty' are complete and total.