おか

/woka/ → /oka/

From Old Japanese. Attested in the Kojiki of 712^[1] and the Man'yōshū of 759.^[2]

In turn, possibly originally a compound of 峰 (wo, “high place, a height”) +‎ 処 (ka, suffixing element denoting "place").^[1][2]

• (Tokyo) おか [òká] (Heiban – [0])^[3][4][5] (noun)
• (Tokyo) おか [óꜜkà] (Atamadaka – [1]) (proper noun)
• IPA^(key): [o̞ka̠]

おか • (oka) ^{←をか (woka)?}

1. hill

   丘(おか)を下(くだ)る

   oka o kudaru

   to go down a hill

• 岡(おか)山(やま) (Okayama)
• 福(ふく)岡(おか) (Fukuoka)

• 坂(さか) (saka, “slope”)

おか • (Oka) ^{←をか (Woka)?}

1. a surname

Appears to be a shift in sense of 岡・丘 (oka, “hill”). First attested in a text from 1310.^[6]

• (Tokyo) おか [òká] (Heiban – [0])^[3][4]
• IPA^(key): [o̞ka̠]

おか • (oka) ^{←をか (woka)?}

1. [from 1310] land, ground (as opposed to the sea or other bodies of water)

   Synonyms: 陸地 (rikuchi), 陸 (riku), くにが (kuniga), くぬが (kunuga), くが (kuga)

2. [from 1708] the bathing area next to an お風呂 (ofuro, “traditional Japanese soaking tub”), often raised relative to the tub basin
3. [from 1873] the raised portion of a 硯 (suzuri, “inkstone”) where one grinds the stick of India ink (as opposed to the 池 (ike, literally “pond”) or 海 (umi, literally “sea”), the small depressed basin area where one pours in the water)

• おかー (okā)

• IPA^(key): [o̞ka̠]

おか • (oka) 

1. (Internet slang) short for おかえり (okaeri): welcome back, welcome home