If you meant to type "brighten" but misspelled it as "brighteen", here are a few suggestions to correct the mistake: 1) "brighten" - the correct term; 2) "brighter" - describing something with more brightness; 3) "brightening" - the action of increasing brightness; 4) "brightened" - when something has already become brighter. Remember to proofread to avoid such misspellings in the future.