a.

1. 不规则的，无规律的；不稳定的
   The trains from here are irregular.

   从这里开出的火车是无规律的。

   These procedures are highly irregular.

   这些程序是很不合乎规则的。

2. 不合法的；不合道德的；非正规的
   It is an irregular document.

   这是一份非正式文件。

3. 不平整的；不对称的；不笔直的
   Braces straightened the girl's irregular teeth.

   畸形矫正钢丝架平正了这女孩不整齐的牙齿。

4. 【美】（商品）次品的，处理品的
5. 【经】（行市）涨跌不定的
6. 【语】不规则（变化）的
   The verbs "keep" and "see" are irregular in their inflections.

   “keep”与“see”这两个动词的词形变化是不规则的。

n.[C]

1. 不规则物；非正规人员；不正常者
2. 非正规兵[P]
   Hundreds of the irregulars deserted.

   数以百计的非正规兵开了小差。

3. 【美】不合规格的产品[P1]

adj.

1. not regular in shape, arrangement, or occurrence.
2. contrary to a rule, standard, or convention.
   ▸not belonging to regular army units.
3. Grammar  (of a word) having inflections that do not conform to the usual rules.

n.

1. a member of an irregular military force.
2. chiefly N. Amer. an imperfect item of merchandise sold at a reduced price.