I. (h)wiˈchevə(r) pronoun
Etymology: Middle English which ever, from which (II) + ever
: whatever one or ones out of a group : no matter which one or ones
would like to speak to your father or your mother, whichever is at home
take two of the four elective subjects, whichever you prefer
enter law or some other profession, but whichever you choose, put your whole heart into it
II. adjective
: being whatever one or ones out of a group : no matter which
walk … back to whichever chair he happened to be using at the time — Grace Metalious
a general reserve fund out of which additional advertising money could be drawn to back whichever books need it — Publishers' Weekly
its soothing … effect will be the same whichever way you take it — Punch