lie
謊 centers on falsehood: a spoken lie or untruth. The meaning is straightforward and does not branch into distinct senses.
謊 combines 言 (speech) with 荒, which likely contributes the sound and may carry a sense of wildness or disorder, fitting the idea of a lie as a wild or untruthful statement.
Words (言) that are wild and overgrown like a wasteland (荒) are lies: 謊 is a lie.
For コウ, imagine a lie spreading like a cough through a crowd: cough -> コウ, and the wild words infect everyone.