This is something that's very common in English. The - ed suffix is added to a noun or nominal to form an adjective which can then be used to modify a noun, as in one-armed bandit . The suffix is identical to that used to form a regular past participle, though the adjective that's formed is not actually a past participle.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.