1. To estimate an unknown value or quantity on the basis of the known range, esp. by statistical methods.
2. To deduce an unknown legal principle from a known case.
3. To speculate about possible results, based on known facts. — extrapolative (-lay-tiv or -l[ schwa]-tiv), extrapolatory (-l[schwa]-tor-ee), adj. — extrapolator (-lay-t[schwa]r), n.