V. S. Apte, The Practical Sanskrit–English Dictionary. Look up any word of the Gita in Devanagari, IAST or Harvard-Kyoto, or browse the headwords letter by letter.
Entry वै
वैvai1 P. (वायति)
1 Parasmaipada (वायति)
To dry, be dried.
To be languid or weary, be exhausted.
Derived forms and compounds
वैvai, Indeclinable A particle of affirmation or certainty (indeed, truly, forsooth), but it is generally used as an expletive; आपो वै नरसूनवः Ms.1.1;2.231;9.49; 11.78 etc. It is also said to be a vocative particle, and sometimes shows entreaty or persuasion (अनुनय).