Modern niŭ, Middle Chinese ɳuw (Pulleyblank), Old Chinese *nuʔ (Zhengzhang Shangfang). Character etymology: phono(丑)-semantic(糸). Original senses: "loop handle, handling loop (of a utensil)" (Rites of Zhou), "button" (Classic of Rites), "origin, basis" (Zhuangzi), "classifier for seals" (Book of Zhou). Derived senses: "to tie", "to link, to connect".
Note: This word family is very likely derived from a word meaning "nose". Compare Tibetan སྣ (sna, "nose"), as well as Tibetan རྣ (rna, "ear") (These are likely cognate, compare Chinese 聞 (wén, OC *mɯn, "to hear; to smell")). Also compare Proto-Indo-European *nā́s, *(H)néh₂s (< **sna, "nose"), possibly from a root meaning "to flow", which produced English sn-words such as "snout, snort, sniff, snuff, sniffle, snuffle, snore, snitch, sneeze, snot".
"Nose" in Old Chinese was 鼻 (bí, OC *blids, "nose"), a differentiated form of 自 (zì, OC *sbids, "self < nose", note the graphical resemblance to a nose). Graphical derivations from this include: 臭 (chòu, OC *kʰljus, "unpleasant smell", graphically: smell of a dog), 臭, 嗅 (xiù, OC *qʰlus, "to smell, to sniff").