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.
presence. n. 1. the state or fact of being present. 2. the immediate proximity of a person or thing. 3. personal appearance or bearing, esp of a dignified nature. 4. an imposing or dignified personality.