Ladder-proof refers to material that is resistant to ladder runs or snags. In other words, it's a term used to describe textiles which are durable and don't easily get torn or stained. The antonyms of this word, therefore, would be adjectives that describe materials that are not strong or resistant. Some examples could be flimsy, weak, fragile, delicate, or easily destructible. These materials, unlike ladder-proof ones, are more susceptible to tears, snags, and runs. In essence, ladder-proof fabrics are a desirable characteristic in clothing, especially in hosiery, as they add to the durability and longevity of the garment.