trim: attitude of an aircraft in flight when allowed to take its own orientation
abstraction: a general concept formed by extracting common features from specific examples
gram's method: a staining technique used to classify bacteria; bacteria are stained with gentian violet and then treated with Gram's solution; after being decolorized with alcohol and treated with safranine and washed in water, those that retain the gentian violet are Gram-positive and those that do not retain it are Gram-negative