To snap the fingers—in assent, in joy, in warning; a measure of time equal to twenty winks.

A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous

彈指 (tán zhǐ) 　( “snap of the fingers; a small unit of time, instant, a jiffy” )

{《漢語大詞典》4.153b(佛典)} ; {《大漢和辞典》770a(舊唐書)} ;

Dharmarakṣa: {124a19} 彈指之頃自然有聲，靡不通達。十方佛國、一切世界六反震動(p)

{K.388.8} acchaṭā-saṃghāta-

Kumārajīva: {L.51c23} 彈指

Dharmarakṣa: {124c5} 又聖導師 興一大光 彈指之頃 宣洪音聲 即時普告 一切佛土 周遍十方 諸佛世界(v)

{K.392.6} acchaṭā~

Kumārajīva: {L.52b4} do. 

A Digital Edition of A Glossary of Dharmarakṣa translation of the Lotus Sutra by Seishi Karashima, 1998