Prefix · position · below
Means "below" or "beneath a threshold": infrastructure, infrared, infrasound, infrasonic.
Written by Bryan López, English teacher · Updated
Infra- comes from the Latin infra, which means "below" or "underneath". It shows that something is below a limit, a level or a structure. Many times it talks about what supports everything from below, or about what lies below what we can perceive.
Infra- appears mostly in science and technology, where it describes what lies below a threshold or what supports a system from underneath. It is easy to remember through its opposite, ultra-: ultra- goes beyond a limit, while infra- stays below it. If you can picture a line that something sits under, you have the idea.
Combines with nouns and adjectives to mean "below" in level, position, or scale:
Pronunciation: /ˈɪn.frə/. Do not confuse with in- (negation) or inter- (between).
infra-/ˈɪn.frə/
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Separate prefixes with separate origins: in- (negation) from Latin "in-" (not/without); infra- from Latin "infra" (down/below). Tip: if the word means the opposite of something, it is in-; if it means something is beneath a level, it is infra-.
A trick to remember it
Picture something hidden below the visible surface: infra- = below. infrared, infrastructure.
Exercise 1 · Form the word
Exercise 2 · Pick the right one
What do infrared cameras detect?
The prefix infra- means "below" or "beneath a threshold": infrastructure, infrared, infrasound, infrasonic.
The prefix infra- is pronounced /ˈɪn.frə/. For example, "infrastructure".
"structure" becomes "infrastructure". It is a typical example of the infra- prefix.
un-, re-, pre-, dis-, over-, in-... every beginning you need to unlock thousands of English words at once.