劣弧 is read as れっこ (rekko) and means minor arc.
れっこ
rekko
れっとうかん
inferiority complex
おとる
to be inferior to
れっか
(visible) aging
れっせい
inferiority (e.g. numerical)
れつあく
inferior
れっせいがく
dysgenics
れっせいいでんし
recessive gene
れつけっていけい
underdetermined system
れっせいいでんけいしつ
recessive trait
れっせいけいしつ
れつごかぶ
deferred stock
れっせいいでん
recessive heredity