whose

Etymology

From Middle English whos, from Old English hwæs, from Proto-Germanic *hwes, genitive case of *hwaz (“who”) *hwat (“what”).

det

1. (interrogative) Of whom, belonging to whom; which person's or people's.
   Whose wallet is this?
2. (relative) Of whom, belonging to whom.
   This is the man whose dog caused the accident. (= This man's dog caused the accident.)
   Venus, whose sister Serena is, won the latest championship.
   The most rapid and most seductive transition in all human nature is that which attends the palliation of a ravenous appetite.[…]Can those harmless but refined fellow-diners be the selfish cads whose gluttony and personal appearance so raised your contemptuous wrath on your arrival? 1922, Ben Travers, chapter 5, in A Cuckoo in the Nest
3. (relative) Of which, belonging to which.
   We saw several houses whose roofs were falling off. (= The roofs were falling off several houses that we saw.)

pron

1. (interrogative) That or those of whom or belonging to whom.
   Several people have lost their suitcases. Whose have you found?
2. (relative) That or those of whom or belonging to whom.
   This car is blocking the way, but Mr Smith, whose it is, will be here shortly.
   If he starts it on another man's lands, and kills it there, it belongs to the owner of the land; but if he start game on one man's lands, and pursue it to those of another, and kill it there, it is neither the property of the man on whose lands it is started, nor of him on whose it is killed, but belongs to the killer. 1833, Tait's Edinburgh Magazine, Volume 3, page 637 (Google Books view)
   The notes on authors are extremely brilliant and incisive, not always in good perspective and sometimes freaky in their wit, as, for instance, the reference to Mrs. Holmes, of whose books it is said, "The secret of their long popularity has never been divulged by their readers," and Mrs. Harris, of whose it is said, "To a lively mind they should be conducive of profound sleep," which, whatever its faults, is by no means true of "Rutledge." 1895, Library Journal, Volume 20, page 397 (Google Books view)