knotty (Adjective) — Making great mental demands; hard to comprehend, solve or believe. ex. "I faced the knotty problem of what to have for breakfast"
knotty (Adjective) — Used of old persons or old trees; covered with knobs or knots. ex. "knotty and knotted hands"
knotty (Adjective) — Highly complex or intricate and occasionally devious. ex. "a knotty problem"
knotty (Adjective) — Tangled in knots or snarls. ex. "knotty thread"