The word "knuckles" is spelled with a silent "k" at the beginning, followed by a "n" sound, represented in IPA phonetic transcription as /n/. The next sound is a palatal fricative, represented as /x/, followed by a close-mid back rounded vowel, represented as /ʊ/. The final sound is a voiceless alveolar stop, represented as /t/. Thus, the correct spelling of this word is "knuckles", not "nuckles". This word refers to the bony prominences on the back of the hand.
The word "knuckles" can be traced back to Middle English, where it was spelled "knokel" or "knokles". It originated from the Old English word "cnēoclas", which meant "little bones". The Middle English form later transformed into "knokels" and eventually "knuckles" in modern English. The term refers to the joints of the fingers or toes, particularly the ones that protrude when a fist is made.