अपि

Monier-Williams · api
ápi or sometimes pi ( pi-dṛbh, pi-dhā, pi-nah), expresses placing near or over, uniting to, annexing, reaching to, proximity, &c. [ ? Zd. api ; Germ. and Eng. prefix be] ‖ in later [55, 1] Sanskṛit its place seems frequently supplied by abhi. (As a separable adv.) and, also, moreover, besides, assuredly, surely ‖ api api, or api-ca, as well as ‖ na vâpi or na apivā or na nacâpi, neither, nor, câpi, (and at the beginning of a sentence) api-ca, moreover

Monier-Williams · api
api is often used to express emphasis, in the sense of even, also, very ‖ e.g. anyad api, also another, something more ‖ adyâpi, this very day, even now ‖ tathâpi, even thus, notwithstanding ‖ yady api, even if, although ‖ yadyapi tathâpi, although, nevertheless ‖ na kadācid api, never at any time: sometimes in the sense of but, only, at least, e.g. muhūrtam api, only a moment

Monier-Williams · api
api may be affixed to an interrogative to make it indefinite, e.g. ko'pi, any one ‖ kutrâpi, anywhere

Monier-Williams · api
api imparts to numerals the notion of totality, e.g. caturṇam api varṇānām, of all the four castes