The phrase "deep dive"

A deep dive is a close look at one subject. The phrase comes from diving, and dictionaries now record both senses side by side.

What it means

The Oxford Learner's Dictionaries define a deep dive as "a detailed examination of a subject". Oxford's editors mark it as informal.

Wiktionary gives "An in-depth examination or analysis of a topic", and dates this sense from the 1990s.

From the water

The first sense in Wiktionary is literal, "An act of deep diving". Oxford's entry for the noun dive has the same sense in its example "We did a deep dive to see if we could find the wreckage."

Into or on

Wiktionary notes the phrase is often followed by "into" or "on". Oxford gives one example of each.

People "take" a deep dive in Oxford's first example and "do" one in the second.

As a verb

Wiktionary also lists deep-dive as a verb, with a hyphen. Its past tense is deep-dived, and Wiktionary records deep-dove as chiefly American.

The verb can take an object directly. Wiktionary quotes the film-maker David Michod, at the Venice Film Festival in 2019: "We deep-dived the research and then made a whole bunch of stuff up."

Two words or a hyphen

Oxford spells the noun as two words, deep dive. Wiktionary lists deep-dive, with a hyphen, as an alternative form of the noun and as the main form of the verb.

How to say it

Oxford gives the pronunciation as /ˈdiːp daɪv/. The stress falls on "deep", which sounds like the ordinary word, and "dive" rhymes with "five".

Where the words come from

Both halves are Old English, according to Oxford. "Deep" comes from dēop. "Dive" comes from dūfan, meaning "dive, sink", and dȳfan, meaning "immerse".

Oxford adds that the two words are related to each other, and to "dip".

The phrase in a sentence

These example sentences are our own.

Sources