天馬行空 てんばこうくう Meanings Expression unconstrained creativity; bold and imaginative (literally: (like a) a heavenly steed soaring across the skies) Kanji 天 heaven. Read as テン. 馬 horse 行 go. Read as コウ. 空 sky. Read as クウ. Word lists Yojijukugo (四字熟語) Jinuma: Japanese Dictionary · Word lists