There are many ways to find out words using particular letters. There are plenty of "online anagram machines" on web sites such as these where you can input the letters from which you would like to find a word and they will provide you with a list of all the words that exist from the selection of letters provided. For the letters A N I S P R C O A, unfortunately there is only one nine letter word that can be produced that has a meaning in the English language. This word was found using Wolfram Alpha, a very good free online computational search engine. By inputting "anagram ANISPRCOA" you can discover that the word "caparison" is the only word that can be made from those nine letters. I have verified this by using other anagram machines online, which have confirmed that caparison is the only word that can be made from the nine letters A N I S P R C O A. The word "caparison" is not a very common word in the English language, used only when referring to horses. A caparison is a decorated covering for a horse, and also traditionally for a war horse. This covering is a cloth that is spread over the saddle or harness of a horse and is often gaily ornamented. The word caparison can also be used as a transitive verb where its definition is "to put trappings on". This however is a rarely used word and very uncommon outside of the military.
References:
definr.com/caparison, www.wolframalpha.com/input/?i=anagram+ANISPRCOA
References:
definr.com/caparison, www.wolframalpha.com/input/?i=anagram+ANISPRCOA