Thanks (twice!) ixion. There are two wiki spellings that fit, one ending in 'us', one in 'os'. This makes 15a: Weather feature, unknowingly seen as a basis for faith(3,5)
T?E?L?U? or T?E?L?O?. Do you think the answer is The flood? By the way, if you put T?E?L?U? in www.onelook, you get The loup-one letter short!!