A word formed by using the letters of another word is called an anagram.
Using only the first letters of a word to form a new word or phrase is called an acronym.
blowed, bowled
Prose
The letters of the word dream can be rearranged to spell the word armed.
The letters ietremny do not all form one word and you cannot spell the name of an insect using all of the letters. You can spell mite using some of the letters.
All letters used, you can form the word: import.
Unless you have other letters you're not telling us about, a word using "these" letters is "sheet."
The word is sterns
The letters spell the word card.
The word "river" can be spelled by using five letters from the word "university."
There is no English word that uses all 7 of these letters. The longest word using these letters in unreel. The longest word using the j is jurel.