Collins COBUILD Advanced Learner's English Dictionary - deadly

(deadlier, deadliest) 1. If something is deadly, it is likely or able to cause someone’s death, or has already caused someone’s death. He was acquitted on charges of assault with a deadly weapon. ...a deadly disease currently affecting dolphins... Passive smoking can be deadly too... = lethal, fatal ADJ 2. If you describe a person or their behaviour as deadly, you mean that they will do or say anything to get what they want, without caring about other people. The Duchess levelled a deadly look at Nikko. ADJ c darkgreen]disapproval 3. You can use deadly to emphasize that something has a particular quality, especially an unpleasant or undesirable quality. Broadcast news was accurate and reliable but deadly dull... = deathly ADV: ADV adj c darkgreen]emphasis 4. A deadly situation has unpleasant or dangerous consequences. ...the deadly combination of low expectations and low achievement... ADJ: usu ADJ n 5. Deadly enemies or rivals fight or compete with each other in a very aggressive way. The two became deadly enemies... ADJ