a.

1. 不規則的，無規律的；不穩定的
   The trains from here are irregular.

   從這裡開出的火車是無規律的。

   These procedures are highly irregular.

   這些程序是很不合乎規則的。

2. 不合法的；不合道德的；非正規的
   It is an irregular document.

   這是一份非正式文件。

3. 不平整的；不對稱的；不筆直的
   Braces straightened the girl's irregular teeth.

   畸形矯正鋼絲架平正了這女孩不整齊的牙齒。

4. 【美】（商品）次品的，處理品的
5. 【經】（行市）漲跌不定的
6. 【文】不規則（變化）的
   The verbs "keep" and "see" are irregular in their inflections.

   "keep"與"see" 這兩個動詞的詞形變化是不規則的。

n.[C]

1. 不規則物；非正規人員；不正常者
2. 非正規兵[P]
   Hundreds of the irregulars deserted.

   數以百計的非正規兵開了小差。

3. 【美】不合規格的產品[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.