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。

ir.reg.u.lar

adj.Abbr. irreg.（形容词）缩写 irreg.
Contrary to rule, accepted order, or general practice:
不合规则的：与法规、既定规则或习惯做法相背的：
例句：
irregular hiring practices.
不规范的雇佣

Not conforming to legality, moral law, or social convention:
不法的，违规的：不合法律、道德准则或社会习惯的：
例句：
an irregular marriage.
不合法的婚姻

Not straight, uniform, or symmetrical:
不规则的，异常的：不符常规的、不统一的或不对称的：
例句：
irregular facial features.
不规则的脸部特征

Of uneven rate, occurrence, or duration:
不稳定的，无规律的：频率、出现或持续时间不稳定的：
例句：
an irregular heartbeat.
心律不齐

Deviating from a type; atypical.
背离一种类型的；非典型的
Botany Having differing floral parts, as of a zygomorphic or asymmetrical flower.
【植物学】 不规则的：花的组成部分相异的，如两侧对称或不对称的花
Falling below the manufacturer`s standard or usual specifications; imperfect.
不完美的：在制造者的标准或通常要求之下的；不完美的
Grammar Departing from the usual pattern of inflection, derivation, or word formation, as the present forms of the verbbe or the plural noun children.
【语法】 不规则的：背离变形的、派生的或构词的通常程式的，如动词be 的现在时形式或复数名词 children
Not belonging to a permanent, organized military force:
非正规的：不属于永久的，有组织的军队的：
例句：
irregular troops.
非正规军队

n.（名词）
One, such as an item of merchandise, that is irregular.
不合格品，次品：一件不规则的东西，如商品
A soldier, such as a guerrilla, who is not a member of a regular military force.
非正规军：非正规军队成员的士兵，如游击队队员

【引伸】
irreg.ularly
adv.（副词）