Here are some adjectives with opposite meanings, using the prefixes:
- un-: unhappy (opposite of happy)
- dis-: dishonest (opposite of honest)
- in-: inactive (opposite of active), insecure (opposite of secure)
- im-: impatient (opposite of patient), impolite (opposite of polite)
Additionally, here are some other opposites:
- friendly - unfriendly
- reliable - unreliable
- sensitive - insensitive
- organised - disorganised
- punctual - unpunctual
- outgoing - shy
- hard-working - lazy
- flexible - rigid
- enthusiastic - unenthusiastic