平(たい)ら

平(たい)ら is a na-adjective describing surfaces that are flat, level, or even. Figuratively, it can mean calm or peaceful.

FORMS:

• 平(たい)らな + noun: flat (modifier)
• 平(たい)らに + verb: flatly (adverb)
• 平(たい)らにする: to flatten, to level

COMMON COLLOCATIONS:

• 平(たい)らな道(みち): flat road
• 平(たい)らな土地(とち): flat land
• 心(こころ)を平(たい)らにする: to calm one's mind

SIMILAR WORDS:

• 平坦(へいたん): flat, even — more formal, often for terrain or abstract situations (平坦(へいたん)な人生(じんせい))
• 滑(なめ)らか: smooth — focuses on texture rather than levelness

NOTE:
平(たい)ら is also a common family name (Taira), associated with the famous 平氏(へいし) (Taira clan) from Japanese history.