Middle English (originally denoting a crime or transgression, hence a fine): from Old French forfet, forfait, past participle of forfaire 'transgress', from for- 'out' (from Latin foris 'outside') + faire 'do' (from Latin facere).

• forest from Middle English:

  You would not necessarily link forest and foreign, but they have the same Latin root. Forest came via French from the Latin phrase forestis silva, literally ‘wood outside’, from foris ‘out of doors, outside’ and silva ‘a wood’. The first word moved into English and became our ‘forest’. In early use forest had a special legal sense. It was an area, usually belonging to the king, that was intended for hunting, a mixture of woodland, heath, scrub, and farmland not as thickly wooded as forests today. It had its own forest laws, and officers appointed to enforce them. The New Forest in Hampshire was reserved as Crown property by William the Conqueror in 1079 as a royal hunting area, and still has its own rules and officers, or verderers (mid 16th century), a word that comes from Latin viridis, ‘green’—compare the expression greenwood (Middle English). Forfeit (Middle English) which originally meant ‘a crime or offence’, with the meaning of a fine or penalty developing from this, is also from foris, as are forum, literally ‘what is out of doors’ in Latin, but used to mean ‘market place’ and then ‘meeting place’. Forensic (mid 17th century) comes from Latin forensis ‘in open court, public’, from forum. Because we so often hear the expression forensic science in the context of solving a mystery, it is sometimes forgotten that the term means the application of medical knowledge to support the law.