犀 is a bound form. Key compounds: 犀牛 (xīniú, rhinoceros), 犀利 (xīlì, sharp/incisive — used for speech, eyes, analysis). The 'sharp' meaning comes from rhino horn being considered piercing.
牛 (ox) is the indexing radical, tucked under the body silhouette. Pre-modern Chinese classed rhinoceroses as horned cattle, so the ox radical became the natural lexical home. Rhinos roamed southern China through the Han before being hunted to local extinction; their horn was prized as luxury material.
尾 wraps the top-left as the bulky body of the rhinoceros — historically the upper part depicted hide-and-tail in an enclosing shelter shape, evoking the animal's massive build. Modern strokes preserve this enclosing silhouette over the ox below.
