つばき

⟨tubaki₁⟩ → */tubakʲi/ → /t͡subaki/

From Old Japanese. Appears in the Man'yōshū, completed some time after 759 CE.[1]

Ultimate derivation unknown. Various theories exist, including:

• Possibly from Old Japanese element つば (tsuba, “glossy, shiny”) + 木 (ki, “tree”).

  Although 艶 (tsuya, “gloss, shine”) is verifiable, つば (tsuba, “glossy, shiny”) does not appear in references.[2][3]

  Moreover, the final ki portion in the Old Japanese phonetic spelling of ⟨tubaki₁⟩ does not match the ⟨ki₂⟩ phonetic spelling for 木 (ki, “tree”).

• Possibly a contraction from 艶葉木 (tsuya pa ki, literally “glossy leaf tree”), with rendaku changing the pa to ba.

  The shift from tsuya to just tsu would have had to occur even earlier than the Man'yōshū. There do not appear to be any other terms exhibiting this same shift.

  This theory also suffers from the same phonetic mismatch for the ki portion.

• Possibly borrowed from Korean 동백(冬柏) (dongbaek).

• (Tokyo) つ​ばき [tsúꜜbàkì] (Atamadaka – [1])[2]
• IPA^(key): [t͡sɨᵝba̠kʲi]

つばき or ツバキ • (tsubaki) 

1. 椿, 山茶, 海石榴: the Japanese camellia, Camellia japonica

つばき or ツバキ • (Tsubaki) 

1. a female given name
2. 椿, 山茶: a surname
3. 椿, 山茶: a female given name
4. 椿: a place name

Readings of various names.

• (Tokyo) つ​ばき [tsúꜜbàkì] (Atamadaka – [1])[2]
• IPA^(key): [t͡sɨᵝba̠kʲi]

つばき or ツバキ • (Tsubaki) 

1. 津波木, 津葉木, 鍔木, 椿木: a surname
2. 乙姫, 月羽希, 椿希, 椿樹, 椿生: a female given name
3. 椿姫, 椿有, 翼希, 翼樹, 翼姫: a female given name
4. 翼生: a male given name

Derived as the 連用形 (ren'yōkei, “continuative or stem form”) of now-obsolete verb 唾吐く (tsubaku, “to spit, to expectorate”), itself from 唾 (tsu, “saliva”) + 吐く (haku, “to expel from the mouth: to spit, to vomit, to exhale”).[2][3]

• (Tokyo) つばき​ [tsùbákíꜜ] (Odaka – [3])[2]
• IPA^(key): [t͡sɨᵝba̠kʲi]

つばき or ツバキ • (tsubaki) 

1. 唾: saliva, spit

• Etymology at Nihonjiten (in Japanese)
• Etymology at Gogen-Allguide (in Japanese)