sacro-

compound bone at the base of the spine, 1753, from Late Latin os sacrum "sacred bone," from Latin sacrum, neuter of sacer "sacred" (see sacred). Said to be so called because the bone was the part of animals that was offered in sacrifices. The Late Latin phrase is a translation of Greek hieron osteon. Greek hieros also can mean "strong" (see ire), and some sources suggest the Latin is a mistranslation of Galen, who was calling it "the strong bone."