形容詞 headlong:

1. excessively quick
   同義詞：hasty
2. with the head foremost
   同義詞：headfirst

副詞 headlong:

1. with the head foremost
   同義詞：headfirst
2. at breakneck speed
   同義詞：precipitately
3. in a hasty and foolhardy manner
   同義詞：rashly

1. A headlong dive or fall.
   頭朝下跳水或掉落
2. The child leaned towards his mother and fell headlong in front of her.
   孩子俯身湊向媽媽?zhuān)^朝前面倒在媽媽的面前。
3. Little Marry carried on for ten minutes after she fell headlong.
   小瑪麗摔了個(gè)倒栽蔥后，哭鬧了十分鐘。
4. Don't rush headlong into danger; think it through carefully before you make any decisions.
   不要輕率地奔赴險(xiǎn)境，做任何決定之前都要認(rèn)真想想。

head.long

adv.（副詞）
With the head leading; headfirst:
頭部先著地地；頭沖前地：
例句：
The runner slid headlong into third base.
跑壘者一頭滑進(jìn)了三壘

In an impetuous manner; rashly.
魯莽地；輕率地：用魯莽的方式地；輕率地
At breakneck speed or with uncontrolled force.
飛快地：以極快的速度或無(wú)法控制的力量地
adj.（形容詞）

Done with the head leading; headfirst:
頭在前完成的；頭沖前的：
例句：
a headlong dive.
俯沖跳水

Impetuous; rash.See Synonyms at impetuous
莽撞的；輕率的參見(jiàn) impetuous
Uncontrollably forceful or fast.
無(wú)法控制的力量或速度的
Archaic Steep; sheer.
【古語(yǔ)】 陡峭的；垂直的

來(lái)源：
From Middle English (bi) hedlong
源自 中古英語(yǔ) (bi) hedlong
from hed, head [head] * see head
源自 hed, head [頭部] *參見(jiàn) head