When I first got into Doctor Who and started watching the classic episodes and researching the history of the show, I came across the term "time travel capsule" for TARDISes, and I absolutely hated it. It always seemed woefully inadequate to call the TARDIS a "time machine", because it's so much more than just that. You might call it a "space-time machine", but that's starting to get unwieldy. But "time travel capsule", or TT capsule, is the correct term for the class of ship, and it just rubbed me exactly the wrong way. "Capsule" seemed so demeaning, for such a vast, wondrous craft, and I hated using it. I was supported in feeling that way by my husband, who also hates the term. I used it once in some story, and one of the only comments he made on the story was that seeing that phrase bugged him enough that it ruined immersion.
Somehow, though, I now really love the term. I know why I use it now - David has a TARDIS and it is most certainly not a police box, so I can't use the usual fandom terms of "police box" and "blue box" to refer to it, and as I said before, it's just not a "time machine" to me - but I don't know why my opinion of the term has reversed. It's just weird.