sea

B2 · Upper Intermediate Countable noun

n. a very large number or amount of something that looks like it has no end.

n. a vast or overwhelming quantity of something, used figuratively to suggest immense scale or movement.

日本語:海※

“Looking out from the stage, the singer saw a sea of happy faces.”

“The protesters formed a sea of umbrellas in the square, shielding themselves from the relentless autumn rain while they waited for the announcement.”

B2 · Upper Intermediate Plural noun

n. the movement of the water, especially when it is rough or has big waves.

n. the state of the water's surface in terms of waves and swell, often used in the plural to describe rough conditions.

“The small boat struggled to stay upright in the heavy seas.”

“The captain decided to change course to avoid the high seas reported by the weather station further north.”

C2 · Proficiency Countable noun Science Technical

n. a large, dark, flat area on the surface of the moon.

n. a large, dark basaltic plain on Earth's Moon, historically mistaken for a body of water.

“The Sea of Tranquility is the most famous dark plain on the moon.”

“Early astronomers named these vast basaltic plains 'seas' under the mistaken belief that they were filled with water rather than volcanic rock.”

C2 · Proficiency Countable noun Science Technical

n. a group of particles that constantly appear and disappear inside an atom.

n. a theoretical model of the vacuum or the interior of a hadron consisting of a constant flux of virtual particles.

“Scientists study the sea of quarks to understand how atoms work.”

“The distribution of momentum among the sea quarks provides crucial data for high-energy collision experiments in particle accelerators.”