We found one dictionary that defines the word ultra-low frequency:

General (1 matching dictionary)

1. Ultra-low frequency: Wikipedia, the Free Encyclopedia

▸ Words similar to ultra-low frequency ▸ Usage examples for ultra-low frequency ▸ Idioms related to ultra-low frequency ▸ Wikipedia articles (New!) ▸ Words that often appear near ultra-low frequency ▸ Rhymes of ultra-low frequency ▸ Invented words related to ultra-low frequency