"to cry out, speak with vehemence, make a loud outcry in words," 1560s, a back-formation from exclamation or else from French exclamer (16c.), from Latin exclamare "cry out loud, call out," from ex "out," perhaps here an intensive prefix (see ex-), + clamare "cry, shout, call" (from PIE root *kele- (2) "to shout"). Spelling influenced by claim. Related: Exclaimed; exclaiming.
late 14c., exclamacioun, "a calling or crying aloud; that which is uttered with emphasis or passion, a vehement speech or saying," from Latin exclamationem (nominative exclamatio) "an exclamation" (in rhetoric), "a loud calling or crying out," noun of action from past-participle stem of exclamare "cry out loud" (see exclaim).
The punctuation symbol known as the exclamation point (1824) or exclamation mark (1926) was earliest called an exclamation note or note of exclamation (1650s); Shakespeare has note of admiration (1611). Another name for it was shriek-mark (1864). The mark itself is said to date to c. 1400 among writers in Italy and to represent the Latin io!, an exclamation of delight or triumph, written with the -i- above the -o-.
It forms all or part of: acclaim; acclamation; Aufklarung; calendar; chiaroscuro; claim; Claire; clairvoyance; clairvoyant; clamor; Clara; claret; clarify; clarinet; clarion; clarity; class; clear; cledonism; conciliate; conciliation; council; declaim; declare; disclaim; ecclesiastic; eclair; exclaim; glair; hale (v.); halyard; intercalate; haul; keelhaul; low (v.); nomenclature; paraclete; proclaim; reclaim; reconcile.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit usakala "cock," literally "dawn-calling;" Latin calare "to announce solemnly, call out," clamare "to cry out, shout, proclaim;" Middle Irish cailech "cock;" Greek kalein "to call," kelados "noise," kledon "report, fame;" Old High German halan "to call;" Old English hlowan "to low, make a noise like a cow;" Lithuanian kalba "language."