Ante - anti
The two prefixes ante and anti sound exactly the same. The difference is that ante means 'before', and anti means 'against'.
- Ante is a prefix derived from a Latin word. It can be used as 'before' in connection with both time ('antediluvian'~ before the Flood, i.e Noah's Flood, in Christian, Islamic and Jewish writings) and place: an 'antechamber' is a room that one enters before entering the main chamber - in other words, a waiting room.
- The prefix anti comes from Greek. It has a general meaning of 'against', so 'anticlockwise' means 'in the opposite direction from the way a clock turns'.
Because they sound alike, these two can be confused. 'Ante-war' means before (a particular) war; anti-war means against war (usually in general). In American English, ante-bellum usually refers to the society and culture of the southern states before the Civil War (1861-65).
Confusingly, some words became part of the English language before spelling became fixed, in which the meaning 'before' was spelled with an i. OED lists "antibrachial, anticamera, antichamber, anticipate" as examples.