平ら

た (ta-) +‎ 平 (hira).^[1] (This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium. Particularly: “What is た-? Is it Old Japanese or Modern?”)

Attested in the Nihon Shoki (720 CE). The Ruiju Myōgishō (late Heian period) gives two readings for 平, タヒラ (tahira, modern taira) and タヒラカ (tahiraka); it is not clear whether the two had different meanings.^[1]

平(たい)ら • (taira) ^{←たひら (tafira)?}-na (adnominal 平(たい)らな (taira na), adverbial 平(たい)らに (taira ni))

1. flat, even, level, smooth, having no variation in altitude

   平(たい)らな道(みち)

   taira na michi

   a smooth trail; a flat road

2. stable, calm, at peace

   心(こころ)を平(たい)らにする

   kokoro o taira ni suru

   have a tranquil mind

3. relaxed, lacking formality

   お平(たい)らに

   o-taira ni

   Please make yourself comfortable.

平(たい)ら • (taira) ^{←たひら (tafira)?}

1. flatness
   • 1994, Vogue Japan, Shin teami kyōsokubon, page 116:

     カーブの始(はじ)めと終(おわ)りには、必(かなら)ず平(たい)らがある。

     Kābu no hajime to owari ni wa, kanarazu taira ga aru.

     At the beginning and the end of the curve, there is always some flatness.

   • 2013, Sakura Tsuyoshi, Indo nante mo zettai ni iku ka boke!, page 11:

     「とりあえずあとひと登(のぼ)りすれば、平(たい)らな道(みち)になるから。 」
     「たいら！平(たい)らが一(いち)番(ばん)！！」
     「おまえ昨日(きのう)は『平(たい)らが好(す)きじゃない』って言(い)ってなかったっけ？」
     「それは女(じょ)子(し)のバストの話(はなし)だろうっっ！！」

     “Toriaezu ato hito nobori sureba, taira na michi ni naru kara. ”
     “Taira! Taira ga ichiban!!”
     “Omae kinō wa “taira ga suki ja nai” tte ittenakatta kke?”
     “Sore wa joshi no basuto no hanashi darō!!”

     “If we just climb one more hill, then it becomes a smooth trail.”
     “Level ground! Flat is the best!!”
     “Hey, didn’t you say yesterday, ‘I don’t like flatness?’”
     “That was about girls’ chests!!”