Atoms of the same element that have different masses are called isotopes. Different masses result when there are different numbers of neutrons. All atoms of a particular element have the same number...
Definition of absent. 1 : not present at a usual or expected place : missing was absent from class today sharing memories of absent friends She was conspicously absent [=her absence was very noticeable] at the meeting. absently. adverb He replied absently to her question. Examples of absent in a sentence.
An exclusion is an instance of leaving something or someone out. If you love someone to the exclusion of all others, he or she is the only one for you! Exclusion is closely related to some words that have a positive or negative feel. The word exclusive implies something is high-end, desirable, and not for ordinary people. If someone is excluded, on the other hand, it means that someone has been deliberately and painfully left out.