"angry, inclined to wrath," 1707, from Late Latin iracundus, from ira "anger, wrath, rage, passion" (see ire (n.)). Related: Iracundulous (1765).

[T]he Severn is so mischievous and cholerick a river, and so often ruins the country with sudden inundations, since it rises in Wales, and consequently participates sometimes of the nature of that hasty, iracund people among whom 'tis born. [Thomas Browne, "Letters from the Dead to the Living," 1707]

late 14c., from Old French irascible (12c.) and directly from Late Latin irascibilis, from Latin irasci "be angry, be in a rage," from ira "anger" (see ire).

Irascible indicates quicker and more intense bursts of anger than irritable, and less powerful, lasting, or manifest bursts than passionate. [Century Dictionary]

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."

1580s, "of the nature of Egyptian monumental writing," from Late Latin hieroglyphicus, from Greek hieroglyphikos "hieroglyphic; of Egyptian writing," from hieros "sacred" (see ire) + glyphē "carving," from glyphein "to carve" (from PIE root *gleubh- "to tear apart, cleave").

Plutarch began the custom of using the adjective (ta hieroglyphika) as a noun in reference to the Egyptian way of writing. The noun use of hieroglyphic in English dates to 1580s (hieroglyphics). Related: Hieroglyphical; hieroglyphically.