irregular

irregular, casual, informal

这些形容词均有“非正式的、非正规的”之意。
irregular: 指不按常规、固定模式或计划做事；或指不隶属于任何机构或组织。
casual: 指不太注意场合，仪表等，随意性强。
informal: 指语言、穿着等随便，也指不举行任何形式或仪式的活动。

名词 irregular:

1. a member of an irregular armed force that fights a stronger force by sabotage and harassment
   同义词：guerrilla, guerilla, insurgent
2. merchandise that has imperfections; usually sold at a reduced price without the brand name
   同义词：second

形容词 irregular:

1. contrary to rule or accepted order or general practice
2. (of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
3. not occurring at expected times
   同义词：unpredictable
4. (used of the military) not belonging to or engaged in by regular army forces
5. deviating from normal expectations; somewhat odd, strange, or abnormal
   同义词：atypical
6. lacking continuity or regularity
   同义词：temporary
7. of a surface; not level or flat
8. independent in behavior or thought
   同义词：maverick, unorthodox

1. She tested the whole class on irregular verbs.
   她对全班学生进行不规则动词测验。
2. This dictionary has several appendices, including one on irregular verbs.
   这部词典有几项附录，包括不规则动词附录。
3. The irregular lengthening of a normally short syllable.
   一个正常情况下短音节的不规则的延长
4. Irregular facial features.
   不规则的脸部特征
5. The coastline in this area is quite irregular.
   这个地区的海岸线非常不整齐。
6. To go away without telling your father is most irregular.
   不跟你父亲打个招呼就走是非常不合适的。