off the cuff

adj. in an improvised manner, without preparation, in a spontaneous manner, impromptu

adv. instinctively, automatically, immediately

Ad libitum is Latin for "at one's pleasure"; often shortened to 'Ad lib' (as an adjective or adverb), or 'ad-lib' (as a verb or noun). There is a less commonly used synonym, a bene placito.
See more at Wikipedia.org...

Adverb
1. without preparation; "the presidential candidate made a remark off the cuff"

Adjective
1. with little or no preparation or forethought; "his ad-lib comments showed poor judgment"; "an extemporaneous piano recital"; "an extemporary lecture"; "an extempore skit"; "an impromptu speech"; "offhand excuses"; "trying to sound offhanded and reassuring"; "an off-the-cuff toast"; "a few unrehearsed comments"
(synonym) ad-lib, extemporaneous, extemporary, extempore, impromptu, offhand, offhanded, unrehearsed
(similar) unprepared

quickly, without thinking Off the cuff, I'd say there are 75 applicants. That's my guess.

off-the-cuff /'ɔ:fðə'kʌf/
tính từ (thông tục) ứng khẩu, không chuẩn bị trước (bài nói...)
(C) 2007 www.TừĐiểnTiếngViệt.net