Why is the segment of the IR spectrum below 1500 wavenumbers called the fingerprint region?
I guess the naming "fingerprint region" results from the fact that while I can immediately identify amine, alcohol, carbonyl groups, double and triple bonds and so on in the "upper" and "middle" part of the IR spectrum, the peaks observed in the fingerprint region are often arising from vibrations that are very specific to the very compound you are looking at, thus a "fingerprint" of your compound.