Correct spelling for the English word "Stelled" is [stˈɛld], [stˈɛld], [s_t_ˈɛ_l_d] (IPA phonetic alphabet).
There isn't sufficient information available to determine the etymology of the word "stelled". It could potentially be a rare or obscure term, a neologism, or a misspelling. Without additional context or clarification, it is challenging to provide an accurate etymology.