What does lookup mean?
A lookup is a targeted search for information, usually in a dictionary, directory, database, or other reference source. The word is especially common in computing, where a lookup means retrieving data from a table, index, or database using a key. As a verb, “look up” means to consult a source or search for something, while “look someone up” can also mean find information about a person. The noun form is commonly used with terms such as “dictionary lookup” and “table lookup.” In everyday English, “look up” is usually written as two words, whereas the closed form “lookup” feels more technical and is especially natural in descriptions of systems and data retrieval. Although lookup is not normally a word with a strong positive or negative connotation, it conveys efficiency and precision: a good lookup produces the needed answer without unnecessary searching.
An act of searching for or retrieving information, especially in a dictionary, database, or other reference source.
"The directory was arranged to make each customer lookup quick."
The closed form is particularly common in computing, data processing, and reference-information contexts.
To search for and find information, especially by consulting a reference source or system.
"Students can look up unfamiliar words in the glossary."
In formal and everyday written English, the usual spelling is the two-word phrasal verb “look up.”
The plural is used for separate searches or retrieval operations, especially in computing and information systems.
"The application performs thousands of lookups each second."
A lookup turns a question into a destination: one quick search can replace hours of guessing.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does lookup come from?
Lookup is a compound formed in English from “look” and the adverb “up,” originally expressing the action of raising one's eyes or seeking something. The phrasal verb “look up” developed broader meanings over time, including consulting a source and searching for information. The closed noun form “lookup” became especially established in technical and computing language, where it refers to a retrieval operation. Related English words such as “overlook” and “underlook” share the older root “look.”
Related word forms
How lookup is actually used
As a verb, lookup is usually written as the phrasal verb “look up.” The closed form is common in computing and data-processing contexts, such as “a database lookup,” and is also accepted as a noun.
Easily confused with lookup
Lookup is normally a single word when used as a noun or when referring to a database-style operation, while look up is the standard two-word form of the phrasal verb, as in “look up the answer.”