It's got a number of different licenses for it's various components. LGPL 2.1 is among them.

License file at https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=LICEN...

Source at https://sourceware.org/git/?p=glibc.git;a=summary

I appreciate the correction. It looks like specifically the long double libm functions (things like extended precision square root and logarithm) and the DES implementation from SSLeay are licensed under the LGPL? That seems to conflict with badgersnake's link https://www.gnu.org/software/libc/#license

Someone should update this then. Isn't glibc the poster child for LGPL? https://en.wikipedia.org/wiki/Glibc

That’s not what it says here: https://www.gnu.org/software/libc/#license