(an) arrangement in a straight line

lining up

a step, stage or degree in development

classification, step

two lengths of wood, metal or rope, with crosspieces (called rungs), used to climb up and down

graduated system

one of the thin pieces of hard material that cover the skin of many fish etc; the chalky deposit inside kettles, water-pipes etc; a simple balance or instrument for weighing by comparing something with a known mass; any machine used for weighing

graduated system