Sigh
Lament
noun, する verb
A sigh breath is a sigh.
たんそく
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
他人よりも自分がずっと短足だと気づいた時、彼は深々と嘆息して、日本短足協会へと向かった。
When he realized that his legs were much shorter than other peoples’ he sighed deeply and headed to the Japan Short Leg Association.