Noun:

1. an auxiliary verb (such as `can' or `will') that is used to express modality

Adjective:

1. relating to or constituting the most frequent value in a distribution;

   "the modal age at which American novelists reach their peak is 30"
   

2. of or relating to a musical mode; especially written in an ecclesiastical mode

3. relating to or expressing the mood of a verb;

   "modal auxiliary"
   

averagen.平均数；平均水平adj.平均的；一般的；通常的v.取平均值；达到平均水平

modal auxiliary情态助动词

modal auxiliary verbn.表动词语态的助动词(如may；might；must等)

modal verb情态动词

1. Property dialog boxes can be either modal or modeless.
   属性对话框可以是模态的，也可以是非模态的。
2. Visually differentiate modeless dialogs from modal dialogs.
   视觉上区分非模态对话框与模态对话框。
3. Modal verbs generally take the bare infinitive.
   情态动词通常用不带to 的不定式。