Where does this definition of sound barrier come from?
This entry for sound barrier is sourced from Main Dictionary, one of the dictionaries and corpora merged into Lughet.
Is sound barrier a noun, verb, or something else?
In this entry, sound barrier is tagged as 2n..
What is Lughet?
Lughet is a free trilingual dictionary covering nearly five million entries across Uyghur, Chinese, and English, drawn from more than ten source dictionaries and corpora.