de·tect / diˈtekt/ • v. [tr.] discover or identify the presence or existence of: cancer may soon be detected in its earliest stages. ∎  discover or investigate (a crime or its perpetrators): the public can help the police to detect crime. ∎  discern (something intangible or barely perceptible): Paul detected a faint note of weariness in his father's voice.DERIVATIVES: de·tect·a·ble adj.de·tect·a·bly / -əblē/ adv.

detect †uncover, expose XV; expose the secrecy of XVI. f. dētect-, pp. stem of L. dētegere, f. DE- 6 + tegere cover; after †detect pp. (XIV).
So detection XV. — late L. detective XIX; first in detective police(man); hence ellipt. as sb.