Predict is Latin prae, "before," plus dicere, "to say" — to say beforehand. The prefix pre- is one of the standard Latin prepositions that English uses freely, and dicere is one of the busiest Latin roots in the language, giving dictate, diction, verdict, contradict, edict and dictionary.
English formed the verb in the 1620s, either by back-formation from the older noun prediction or straight from the Latin participle. That order is common: English borrows the abstract noun first, because that is what turns up in learned writing, and then carves out the verb it needs. Interject, interrogate and obstruct all arrived the same way. Predict also shows the -ct- cluster that English preserved from Latin rather than wearing down, as in act, fact and direct.
predict (v.) 1620s (implied in predicted ), "foretell, prophesy, declare before the event happens," a back formation from prediction or else from Latin praedicatus , past participle of praedicere "foretell, advise, give notice," from prae "before" (see pre- ) + dicere "to say" (from PIE root *deik- "to show," also "pronounce solemnly"). Related: Predicted ; predicting . also from 1620s
predict came in through Latin, and its spelling follows that family's conventions.
How that family writes these sounds
| a prefix you can hear on the front | pre-, post-, sub-, trans-, inter-, ex-, re-, de-, ab-, ob-predict, transmit, interject, obstruct |
What gives it away on the page
| pre-, post-, sub-, trans-, inter-, ex-, re-, de-, ab-, ob- | Latin prepositions doing duty as prefixes.predict, transmit, interject, obstruct |