black triangle
class of UFOs, with certain common features which have reportedly been observed during the 20th and 21st centuries
en-GB/ˈblæk ˈtɹaɪæŋɡəl/
en-US/ˈblæk ˈtɹaɪˌæŋɡəl/
class of UFOs, with certain common features which have reportedly been observed during the 20th and 21st centuries