period; a definite length of time marked off by two instants
She checked her email at regular intervals throughout the work day.
Vocabulary like interval appears on the Digital SAT in Words-in-Context questions, where you choose the word that fits a passage's meaning and tone. You can also drill this word with vocabulary flashcards.
excessive and uncontrolled
forceful; possessing or displaying a distinctive feature to a heightened degree
act together; act towards each other; act together or towards others or with others
an unwelcome intruder
middle; lying between two extremes in time or space or state
endless; tiresomely long; seemingly without end
irregular; stopping and starting at irregular intervals
explain; make sense of; assign a meaning to