Does anyone know if there is a connection between 口 and 唇? I see that the latter includes the “mouth” radical, but the other radical doesn’t seem related to the lips at all. I’m wondering if there’s some historical meaning behind びる that would suggest a relationship.
We went over the vocabulary for body parts in my Japanese class recently and I asked my teacher, but she said she never even considered the relationship as a native speaker.
What a mystery 
I don’t know. But sometimes part of he kanji is more related to the pronunciation (onyomi) than the actual meaning.
I didn’t know how to say lips though. Seems easy to remember 
Hmm “sure enough” the onyomi reading of 唇 is しん, just like kanjis that have the same radical (the one that is not 口) - example 地震 (じしん) for earthquake
Excellent resource !
oh nice find! Etymology is so interesting, so I’ll definitely save this website for later! 
The real etymology is above, but for a completely fake one: The びる suffix can be used to mean “to look like, or to appear”.
…
くちびる: Act like a mouth. Ok maybe not really 
Allegedly the びる comes from
縁
The くち (kuchi) element is 口 (“mouth”); several dictionaries, such as Kōjien[1] gloss the meaning of this overall term as 口縁 (kuchiberi), consisting of 口 (kuchi, “mouth”) + 縁 (heri, “edge”). Therefore the current pronunciation kuchibiru may be a shift from an earlier kuchiberi . The h of heri now becomes a b in an instance of rendaku, but may not have in older Japanese.
From wikitionary
Here’s an etymology of the Chinese character
Character decomposition 字形分解 [?]:
Compound 唇 from mouth 口 kǒu and phonetic hoe-plow 辰 chén C089 唇<脣> simp 唇.
Here are 2 others:
形声。音符は蜃 。辰は蜃（はまぐり）のもとの字で、はまぐりなどの貝が足を出して動いている形で、肉片などが動くという意味がある。それに」口（神への祈りの文である祝詞を入れる器の形）を加えて、占いをするの意味であろう。体の部分を示す月（肉）を加えた脣（くちびる）と通用して、「くちびる」の意味に用いる。
Phonological and semantic. Pronounced as 蜃. The original character is 蜃 (hamaguri), and it resembles a clam or other shellfish moving with its legs out, and means pieces of meat moving. Adding a 口 (the shape of a vessel for holding norito, a prayer to the gods) to it suggests it means fortune-telling. Adding meat 月／肉 to the trunk/body of 辰 results in the character 脣 (kuchibiru), which is made by adding 月 (meat), which is commonly used to mean “lips.”
