aerialist vs dervish

aerialist

noun
  • A specialist in aerials, a freestyle skiing discipline. 

  • An acrobat performing high off the ground, defying a fall to earth, as on a trapeze or a tightrope. 

dervish

noun
  • Any irregular guerrilla fighter resembling the Sudanese Mahdi in equipment, uniform, tactics, etc. 

  • A citizen or inhabitant of Darawiish (circa 1895–1920 C.E.), an anti-colonial polity in modern Somalia headed by Sufis. 

  • One of the followers of Muhammad Ahmad, the Mahdi of the Sudan, in the 1880s. 

How often have the words aerialist and dervish occurred in a corpus of books? (source: Google Ngram Viewer )