particle

noun

• 1a minute portion of matter:tiny particles of dust
• [with negative] the least possible amount:he agrees without hearing the least particle of evidence
• Physics another term for elementary particle.
• Physicsanother term for subatomic particle.
• Mathematics a hypothetical object having mass but no physical size.

• 2 Grammar a minor function word that has comparatively little meaning and does not inflect, in particular.
• (in English) any of the class of words such as in, up, off, over, used with verbs to make phrasal verbs.
• (in ancient Greek) any of the class of words such as de and ge, used for contrast and emphasis.