The word "以防" (yǐfáng) is a conjunction formed through lexicalization from classical Chinese grammar, where the character "以" serves as a purpose-marking preposition meaning "in order to" or "so as to," and "防" is a verb meaning "to guard against" or "to prevent." Combined, they create a fixed compound that means "in order to prevent" or "lest," used specifically to introduce a precautionary clause or the negative consequence one seeks to avoid. Its formation follows the common "以 + Verb" pattern to express purpose, and it has solidified into a standard modern Chinese conjunction for indicating preventive measures or intentions.