declare

announce, declare, proclaim, pronounce, advertise, broadcast, publish

这些动词均含“宣布，公开”之意。
announce: 多指首次宣布大家感兴趣或可满足大家好奇心的事情。
declare: 侧重正式就某事清楚明白地宣布。
proclaim: 指官方宣布重大事件或施政方针，语体比announce正式。
pronounce: 词义与announce, declare接近，但较多用于指法律判决方面的宣布。
advertise: 指通过文字和图像资料等的反复宣传而引起公众的注意，有时隐含令人不快或言过其实的意味。
broadcast: 专指利用广播或电视传播消息或发表见解。
publish: 专指通过报刊或其它媒介向公众公布事情。

动词 declare:

1. state emphatically and authoritatively
2. announce publicly or officially
   同义词：announce
3. state firmly
4. declare to be
   同义词：adjudge, hold
5. authorize payments of
6. designate (a trump suit or no-trump) with the final bid of a hand
7. make a declaration (of dutiable goods) to a customs official
8. proclaim one's support, sympathy, or opinion for or against

1. I'm not coming with you and that's final!' declared Mary.
   ｀我不跟你去--这是最後决定!＇玛丽郑重地说。
2. He declared that he was innocent.
   他声称自己是无罪的。
3. I now declare this meeting open.
   我现在宣布会议开幕。
4. Britain declared war on Germany in 1914.
   英国在1914年向德国宣战。
5. The customs asked me if I had anything to declare.
   海关人员问我是否有要报税的东西。

de.clare

v.（动词）
de.clared,de.clar.ing,de.clares
v.tr.（及物动词）
To make known formally or officially.See Synonyms at announce
宣告，公告：正式地或通过官方使…为人所知参见 announce
To state emphatically or authoritatively; affirm.
声称：强调性地或权威式地宣称；断言
To reveal or make manifest; show.
揭示，表明；显示
To make a full statement of (dutiable goods, for example).
申报（例如，可纳税品）
Games To designate (a trump suit or no-trump) with the final bid of a hand in bridge.
【游戏】 最后定约叫牌：打桥牌时通过一手牌的最后的定约叫牌指出（一组王牌或无王牌）
v.intr.（不及物动词）
To make a declaration.
公告：发表宣言，声明
To proclaim one`s support, choice, opinion, or resolution.See Synonyms at assert
宣称：表态支持，表明自己的选择、主张或决心参见 assert

<习惯用语>declare war
To state formally the intention to carry on armed hostilities against.
宣战：正式发表声明意图进入战争状态以反对…
To state one`s intent to suppress or eradicate:
声明意图镇压或消灭：
例句：
declared war on drug dealing in the neighborhood.
向在邻近地段进行的毒品交易宣战

来源：
Middle English declaren
中古英语 declaren
from Old French declarer
源自 古法语 declarer
from Latin dôcl3r3re
源自 拉丁语 dôcl3r3re
dô- [intensive pref.] * see de-
dô- [加强语意的前缀] *参见 de-
cl3r3re [to make clear] from cl3rus [clear] * see kel…- 2
cl3r3re [使…清晰明了] 源自 cl3rus [清晰的] *参见 kel…- 2

【引伸】
declar.able
adj.（形容词）
declar.er
n.（名词）