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

Joined together these UK telescopes can zoom into objects in deep space and see them in incredible detail - with similar resolution to the Hubble space telescope.

From BBC ● Jul. 27, 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

Based on that relationship, greater activity in Purkinje cells would be expected to correspond with lower activity in deep nuclei cells, while reduced Purkinje activity would be expected to have the opposite effect.

From Science Daily ● Jul. 1, 2026

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

From Los Angeles Times ● May 27, 2026

I slide down the wall, sit on the floor taking in deep breaths.

From "Betty Before X" by Ilyasah Shabazz and Renée Watson