Assure/əˈʃʊr/ Definition 1 of 3Pro Tip 1/3Reassuring Phrase Use 'assure' when you want to comfort someone by confirming something positively. I assure you your concerns have been addressed. Pro Tip 2/3Conviction Strength 'Assure' often shows a strong level of personal confidence in your statement. You can be assured that we will meet the deadline. Pro Tip 3/3Formal Context 'Assure' is appropriate in formal situations, like professional or official communications. We assure you of our complete support in this matter.