The noun aggression, with such related words as the adjective aggressive, adverb aggressively, the nouns aggressor and (rarer) aggressee (which AWE does not recommend: see -ee) and the rather unusual verb aggress and technical aggressin (a toxic substance secreted by some micro-organisms to inhibit the defences of their targets) , are all spelled in this way, with two '-g-'s, two '-s-'s - and only one '-r-' in the stem.
- The central meaning is 'attack'. Aggression, particularly in 'an act of aggression', is an unprovoked (military) attack, or opening of hostilities; it may also be a habit of mind, whether military (as e.g. a quality to be valued - or deprecated - in commanders) or more generally as in the characteristic of forceful, even bullying, self-assertiveness. Here it is, says OED, "orig[inally] U.S. ... (Usu[ally] as a positive quality.)" Aggressiveness is perhaps preferable for this state of mind, for which aggressive and aggressively are widely used as descriptors. An aggressor is 'one who attacks', particularly the one who starts a war; an aggressee is the recipient, or victim (more or less passive), of 'unprovoked aggression'.
- Etymological note: the basic root is the Latin aggress-, the past participle form of the verb aggredī 'to attack'.
This is one of the 117 mis-spellings listed as 'Common difficulties' in the section on 'Spelling' within 'Writing' in UEfAP.