[as adv.]with the head foremost 头在前地(的) he fell headlong into the tent. 他一头栽进了帐篷里。
in a rush; with reckless haste 匆忙地(的),草率地(的) [as attrib.adj.]a headlong dash through the house. 匆忙冲着穿过房子。 [as adv.]those who rush headlong to join in the latest craze. 那些匆忙加入最近这股热潮的人。
语源
middle English headling (from head + the adverbial suffix -ling), altered in late middle English by association with -long