InterAction brings together U.S.-based global NGOs to navigate change, coordinate action, and strengthen collective impact in a rapidly evolving humanitarian and development landscape. (General Physics) physics the transfer of energy between elementary particles, between a particle and a field, or between fields. See strong interaction, electromagnetic interaction, fundamental interaction, gravitational interaction, weak interaction, electroweak interaction. InterAction is an alliance of more than 190 international NGOs partnering to eliminate extreme poverty, safeguard a sustainable planet and promote peace. If you interact with someone — by talking, looking, sharing, or engaging in any kind of action that involves the two of you — you can be said to have had an interaction with that person. The meaning of INTERACTION is mutual or reciprocal action or influence. How to use interaction in a sentence. Interaction is action that occurs between two or more entities, generally used in philosophy and the sciences. It may refer to: interaction (countable and uncountable, plural interactions) The situation or occurrence in which two or more things act upon one another to produce an effect; the effect resulting from such a situation or occurrence. INTERACTION definition: 1. an occasion when two or more people or things communicate with or react to each other: 2. an…. Learn more. INTERACTION meaning: 1. an occasion when two or more people or things communicate with or react to each other: 2. an…. Learn more. INTERACTION definition: reciprocal action, effect, or influence. See examples of interaction used in a sentence.