The state or quality of being deep (either physically or metaphorically)(noun)
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Use "deepness" in a sentence
"But there is no heartland, no dark deepness, which is increasingly true of most of Europe, much of Asia, and eastern North America."
"But on individal events, specific talents or flaws come into play, and of course you can find examples of specific skills (memory, "deepness", speed, creativity, musical ability, etc) where someone's specific skills are not the same as their g factor."
"Speakers are above average and they lack "deepness" for a complete sound picture."