impersonal pronoun 
noun
The pronoun it when used without definite reference or antecedent, as in it was snowing and it seems hard to believe.
- prefocussing
- prefogged
- prefogging
- prefoliation
- preform
- preformant
- preformation
- preformationism
- preformationist
- preformative
- preformer
- preformism
- preformist
- pre-Freudian
- prefrontal
- prefrontal leucotomy
- prefrontal lobotomy
- prefulgent
- preg
- pregalactic
- pre-Galilean
- pregame
- pregamic
- pregaming
- preganglionic