in deep

Idioms  

1. Seriously involved; far advanced. For example, He was in deep with the other merchants and couldn't strike out on his own , or She used her credit cards for everything, and before long she was in deep .

2. in deep water . Also, in over one's head . In trouble, with more difficulties than one can manage, as in The business was in deep water after the president resigned , or I'm afraid Bill got in over his head . These metaphoric expressions transfer the difficulties of being submerged to other problems. The first appears in Miles Coverdale's 1535 translation of the Book of Psalms (68:13): “I am come into deep waters.” The second, which also can signify being involved with more than one can understand, dates from the 1600s. Also see over one's head .

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Example Sentences

It’s also located in deep shade, which is very welcome on a hot day.

From Los Angeles Times • May 27, 2026

The manufacturer also warns not to drive in deep, fast-flowing bodies of water such as strong currents or rapids.

From BBC • May 20, 2026

"When you're out in deep space by the Moon, and you are listening to a video they recorded for you before you launch. That's something," the Canadian astronaut told a press conference.

From Barron's • Apr. 9, 2026

They have won pretty much everywhere with a wide range of candidates—in special elections and regular elections in deep red territory and in more contested geographies, running candidates of the far left and the center-left.

From The Wall Street Journal • Apr. 6, 2026

She breathed in deep and, despite the unfamiliar clothes, could still smell her mother’s scent, shea butter lotion and a hint of pencil lead.

From "Ivy Aberdeen’s Letter to the World" by Ashley Herring Blake