Definition of deep

Short definition: The word deep describes something far below the surface or something intense and meaningful. People use it for water, thoughts, emotions, conversations, or experiences that go beyond the obvious and feel serious or powerful.

Looking for a clear and natural explanation of the word deep? The word deep is not just about physical depth like oceans or holes, the word Deep is also widely used to talk about emotions, thoughts, relationships, knowledge, and even silence. Sometimes it describes how far something goes physically, and other times it shows how strong or meaningful something feels inside. Below, each meaning is explained in a relaxed, everyday way, with long examples that sound natural in real conversations.

Comparatives: deeper, deepest
Related: deeply adv., depth n.
Syllable: deep

1. Extending far down from the surface, going much lower than what feels normal or easy to reach.
   The lake was so deep that even experienced swimmers stayed close to the edge, knowing that one wrong move could make it difficult to get back to safety.
   They dug a deep hole in the ground to plant the tree properly, because they wanted its roots to grow strong and last for many years.
   The well is incredibly deep, and it takes several minutes just for the bucket to reach the water below.

   Synonyms: profound, far-reaching, bottomless, sunken, low-lying, steep, hollowed, cavernous, plunging, abyssal, down-reaching, well-below
   Antonyms: shallow, surface-level, flat, high, raised, elevated, thin, skimpy, slight, superficial, low-depth, near-surface

2. Showing strong or intense emotions that feel meaningful and not just on the surface.
   She felt a deep sense of gratitude toward the people who supported her, because she knew she wouldn’t be where she is today without their help.
   His words carried deep emotion, and everyone in the room could feel how serious the moment was.
   They shared a deep connection that went beyond simple friendship and felt more like family.

   Synonyms: intense, heartfelt, sincere, powerful, emotional, meaningful, touching, profound-feeling, soul-level, heartfeltly strong, emotionally rich, deeply felt
   Antonyms: shallow, emotionless, cold, distant, indifferent, superficial, uncaring, lighthearted, casual, detached, unfeeling, hollow

3. Involving serious thought, careful reflection, or ideas that go far beyond simple understanding.
   The book raises deep questions about life and purpose, making readers stop and think long after finishing the last page.
   He enjoys having deep conversations late at night, when people feel more honest and open about what really matters.
   Her explanation was surprisingly deep, even though the topic seemed simple at first.

   Synonyms: thoughtful, insightful, philosophical, reflective, intellectual, serious-minded, analytical, contemplative, perceptive, wise, idea-rich, mentally rich
   Antonyms: shallow-thinking, simple-minded, careless, thoughtless, surface-only, trivial, mindless, empty-headed, basic, unreflective, clueless, naive

4. Lasting for a long time or affecting someone strongly over time, not just for a short moment.
   The loss left a deep mark on her life, shaping the way she looked at relationships and trust.
   His mistake caused deep regret, something he still thinks about years later.
   Growing up in that environment had a deep influence on how he sees the world today.

   Synonyms: lasting, powerful, long-lasting, strongly felt, impactful, far-reaching emotionally, life-shaping, long-term, heavy, meaningful over time, enduring, unforgettable
   Antonyms: temporary, short-lived, light, forgettable, passing, minor, weak, insignificant, fleeting, momentary, shallow-impact, easily forgotten

5. Far inside or far away from the center, often used to describe places, forests, cities, or even situations.
   They found a quiet cabin deep in the forest, far away from noise, traffic, and daily stress.
   The village lies deep in the mountains, where life feels slower and more peaceful.
   He realized he was deep into the project, with no easy way to quit halfway.

   Synonyms: far inside, deeply located, far from edge, remote, hidden away, well within, inward, far-placed, tucked away, buried in, far-reaching inside, isolated within
   Antonyms: near the surface, close by, nearby, on the edge, at the entrance, outer, accessible, easy to reach, visible, upfront, close at hand, open-area

6. (Adverb) Completely or strongly, often used to describe how much someone feels or thinks something.
   I am deeply grateful for everything you’ve done, because your support came when I needed it the most.
   She was deep in thought, barely noticing what was happening around her.
   He is deep in love with her, and everyone can see how much she means to him.

   Synonyms: completely, strongly, intensely, fully, profoundly, seriously, wholeheartedly, strongly inside, to the core, truly, sincerely, absolutely
   Antonyms: slightly, barely, weakly, mildly, superficially, casually, halfheartedly, lightly, faintly, not really, loosely, just a little