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

See Examples For:

in deep

"I am absolutely slathered up in deep heat right now, my legs are tingling," said England's Amy Hunt after securing silver in the 100m.

From BBC ● Jul. 28, 2026

The six candidates for United Nations secretary-general will debate Thursday in the symbolic General Assembly Hall, one week before the formal start of a selection process crucial to an organization in deep crisis.

From Barron's ● Jul. 23, 2026

Together, the two methods allowed researchers to determine precisely when the animals were awake, in deep restorative sleep or in dreaming sleep.

From Science Daily ● Jul. 20, 2026

“I’ve come to admire artists who are willing to go in deep inside their most personal thoughts for the sake of helping the listener understand their own lives,” he said.

From Los Angeles Times ● Jul. 3, 2026

Papa frowned as if he were in deep thought.

From "Summer of the Monkeys" by Wilson Rawls