unto
prep.to or toward something. It is an old-fashioned word that you mostly see in religious books or very formal poetry.
prep.to or toward a person or thing. Archaic in modern prose; primarily used in liturgical, poetic, or highly formal contexts to evoke a sense of gravity or antiquity.
“Do unto others as you would have them do unto you.”
“The ancient king promised to be faithful unto death, a vow recorded in the stone carvings of his tomb.”
“The poet describes a soul surrendering itself unto the infinite, using the archaic preposition to distance the narrative from the mundane language of the everyday world.”
Functions as a preposition; in modern English, it is almost exclusively replaced by 'to' except in fixed idioms or deliberate stylistic archaisms.
“The actual work of translating notes and journals into something the AI can effectively "read" is a technical challenge unto itself, but Cooper has a plan for how to approach it.”
Inherited from Middle English unto, from Old English untō, und tō, equivalent to un- (“against; toward; up to”) + to. Cognate with Old Frisian ont to ("until"; > Saterland Frisian antou (“until”)) (cf. Old Frisian und (“up to; till”), Old Frisian til (“till; to”)), Old Saxon untō, untuo (“until”), Old High German unze, unzi, unza (“until”), Old Norse und (“as far as; up to”), Gothic 𐌿𐌽𐍄𐌴 (untē, “until; as long as”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.