tier

Etymology 1

tie + -er

noun

1. One who ties (knots, etc).
2. Something that ties.
3. (archaic) A child's apron.

Etymology 2

From Middle French tier, from Old French tire (“rank, sequence, order, kind”), probably from tirer (“to draw, draw out”). Alternatively, from a Germanic source related to Middle English tir (“honour, glory, power, rule”), Old English tīr (“glory, honour, fame”), Old Norse tírr (“glory, honour, renown”).

noun

1. A layer or rank.
   Stoke City were playing in the second tier of English football before being promoted to the Premier League.
   Turians have 27 citizenship tiers, beginning with civilians (client races and children). The initial period of military service is the second tier. Formal citizenship is conferred at the third tier, after boot camp. For client races, citizenship is granted after the individual musters out. Higher-ranked citizens are expected to lead and protect subordinates. Lower-ranking citizens are expected to obey and support superiors. Promotion to another tier of citizenship is based on the personal assessments of one's superiors and co-rankers. 2008, BioWare, Mass Effect, Redwood City: Electronic Arts, →OCLC, PC, scene: Turians: Government Codex entry
   At various points during the (too frequent, mostly boring, school play-tier) dialogue. 25 May 23, Nic Reuben, “The Lord of the Rings: Gollum review”, in The Guardian

verb

1. (transitive) To arrange in layers.
2. (transitive) To cascade in an overlapping sequence.
3. (transitive, computing) To move (data) from one storage medium to another as an optimization, based on how frequently it is accessed.