Full Idea
I use the word 'induction' broadly, to cover all the methods we deem reasonable for forming beliefs about the unobserved parts of our world on the basis of experience with the observed parts.
Gist of Idea
Induction is just reasonable methods of inferring the unobserved from the observed
Source
David Lewis (On the Plurality of Worlds [1986], 2.5)
Book Reference
Lewis,David: 'On the Plurality of Worlds' [Blackwell 2001], p.116
A Reaction
Good. Attempts to be precise about it seem to be hopeless and invite paradoxes. Personally I just define it as 'learning from experience', because that makes what we do continuous with the behaviour of other sensible animals.