stimulus

plural stimuluses · plural stimuli

1. An external phenomenon that has an influence on a system, by triggering or modifying an internal phenomenon; for example, a spur or incentive that drives a person to take action or change behaviour.

   an economic stimulus

   2 more examples

   From the beginning of the show to the end, vanity is the sole stimulus and reward of action—vanity, that never looks beyond the present.

   1834, L[etitia] E[lizabeth] L[andon], chapter XV, in Francesca Carrara. […], volume II, London: Richard Bentley, […], (successor to Henry Colburn), →OCLC, page 174

   Democrats, meanwhile, point out that Republicans seem to have made a conscious decision, beginning with the stimulus, to oppose anything the president put forward, dooming any chance of renewed cooperation between the parties.

   2012 November 7, Matt Bai, “Winning a Second Term, Obama Will Confront Familiar Headwinds”, in New York Times

   Synonyms: influence, impetus, impulse, spur, trigger

2. human sciencesSomething external that elicits or influences a physiological or psychological activity or response, or that affects any of the sensory apparatuses.

   to respond to a stimulus

   1 more example

   Even light nonpainful stimuli can provoke or exacerbate spontaneous pain; this is not limited to tactile, thermal, or vibratory stimuli, because auditory, visual, olfactory, and visceral stimuli also may be problematic.

   2002, Kim Burchiel, Surgical Management of Pain, Thieme, →ISBN, page 44

3. biologyA stinging part on the body of a plant or insect.

   Many plants, like many animals, are furnished with arms for their protection; these are either aculei, prickles […]; or stimuli, stings, as in the nettles, which are armed with a venomous fluid for the annoyance of naked animals.

   1789, Erasmus Darwin, The Loves of the Plants, J. Johnson, page 15