Loot and Lute are homophones and easily confused words. The spell-check of most word processing software programs would not catch a slip-up among these three words. As long as it’s a word and it is spelled correctly, spell-check keeps on scanning the document.
Loot is a verb. It means to steal, usually in taking as much as possible in one trip instead of one or two items.
Loot can also be a noun, meaning items that were stolen, and in slang, items that were obtained fairly but at a tremendous deal given their quality or value.
Lute is a noun, it means a medieval predecessor to the acoustic guitar. Lutes are recognizable for having a rounded, bulbous back and a short neck. The people who build and repair guitars are called luthiers. To hear one played, check out this Youtube link by Alan Lowe-Jones.
Lute can also be a verb, meaning to play a lute.
The following sentence uses both words correctly:
The thieves didn’t know what to expect when raiding the museum, so they looted it completely, including a 16th century lute belonging to a Renaissance artist.