holy

Holy entered written English as Old English halig by the 9th century. That form came from Proto-Germanic hailaga-, built from the same base as words for health, luck, and completeness. The older idea was not first moral purity but intactness. What is holy was what had been made whole and inviolate.

In Anglo-Saxon England, halig named saints, relics, feast days, and places under divine protection. Old English texts use it in compounds such as Halig Gast for the Holy Spirit. The adjective carried both awe and safety. It marked what ordinary handling could not claim.

After the Norman Conquest, the form shifted through Middle English spellings such as holi and hali. Its sound and spelling settled toward modern holy between the 13th and 16th centuries. The religious sense grew stronger in church writing, while the older sense of soundness survived in kin such as whole and hale. English kept both histories at once.

Modern holy means sacred, consecrated, or deeply connected with God or ultimate moral reverence. It can also describe intense seriousness, as in holy law or holy vows, and it appears in surprise formulas that have almost lost their religious force. Yet the old root still shows through. Holy is what has been set apart because it is held complete.