class, rank, grade
級 centers on a step or tier in a system: a class, rank, or grade that orders things by level.
級 combines 糸 (thread) with 及, which likely contributes the sound and the idea of reaching or connecting. The thread component suggests a graded series, like steps on a rope or levels of quality in silk.
The left side is thread 糸, and the right side 及 looks like a hand reaching. Imagine a hand pulling a thread through a loom to create different grades of fabric: each pull sets a new class or rank.
For キュウ, picture a queue of students lined up by grade: queue -> キュウ, and each person's rank is marked by their thread-like uniform stripe.
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(school) grade; year; class
high-class; high-grade; high-quality; high-end; luxury
upper level; upper grade; high rank; advanced level; senior level; upper class
classmate
(social) class
(school) class
intermediate level
grade; class; degree; rank; rating; order; points
elementary level; beginner level
lower grade; low class; junior (officer)
highest grade; finest quality; top class
promotion (school, military, etc.)
student in a higher grade; upperclassman
student in a lower grade; underclassman
high grade; special grade; classy
the same grade; same class
classmate; friend in the same class
superlative; extraordinary; mega; outstanding
promotion; advancement
low-grade; low-class; low-quality; vulgar; cheap