Give both forms of the prefix meaning against, opposed to, preventing, relieving.

The two forms of the prefix meaning against, opposed to, preventing, relieving are "anti-" and "contra-".

1. "Anti-" is a prefix meaning against, opposed to, preventing, or relieving. It is used to form compound words. For example, antibiotic (against life, referring to bacteria), antidote (against given, referring to poison), antifreeze (preventing freezing), and antiperspirant (preventing perspiration).

2. "Contra-" is another prefix with a similar meaning. It is used in some medical and scientific terms. Examples include contraceptive (preventing conception), contraindicated (against indication, referring to a reason not to use a certain treatment), and contralateral (opposite side).