gradient vs parados

gradient

noun
  • A slope or incline. 

  • The ratio of the rates of change of a dependent variable and an independent variable, the slope of a curve's tangent. 

  • A differential operator that maps each point of a scalar field to a vector pointed in the direction of the greatest rate of change of the scalar. Notation for a scalar field φ: ∇φ 

  • A gradual change in color. A color gradient; gradation. 

  • The rate at which a physical quantity increases or decreases relative to change in a given variable, especially distance. 

  • A rate of inclination or declination of a slope. 

adj
  • Adapted for walking, as the feet of certain birds. 

  • Moving by steps; walking. 

  • Rising or descending by regular degrees of inclination. 

parados

noun
  • Generally a screen or embankment to protect the rear of a position from enemy attack, from bomb splinters from behind, from enemy fire from a commanding height, or fire from flanking positions. In common English usage since World War II, the term "parados", particularly in trench warfare, has largely been discarded in favour of "rear parapet", which, etymologically speaking, is a contradiction in terms. In some contexts the term "rear traverse" is preferred, but no usage is exclusive. 

  • In trench warfare parados referred to a bank of earth or similar material behind the rear of the trench, opposite the parapet, affording protection from explosions and fragments when shells or bombs overshot the trench. 

  • In fortifications that were enfiladed by enemy in positions commanding the fort, an internal parados could defilade the enemy, serving as physical protection and blindage. Usages of the term have varied inconsistently according to times and sources. Some sources use parados as a synonym for a traverse; some other sources represent parados as a special class of traverse and not necessarily at the back of any particular position. 

How often have the words gradient and parados occurred in a corpus of books? (source: Google Ngram Viewer )