Is there a word for an object that is no longer kept for its original purpose but instead for sentimental value?
mathom /ˈmæðəm/
A lovely, ancient, and eminently modern word for this is mathom. The OED gives for the current sense of mathom:
- A trinket, a piece of bric-a-brac.
But you need to know more about it that just that, for there’s more to it than just that.
Its original sense from Old English is now obsolete:
- A precious thing, a treasure, a valuable gift. Obsolete
For its origin OED notes that:
Etymology: Cognate with Old Saxon mēðom (masculine) precious thing, a treasure, Old Icelandic meiðmar (feminine plural) valuables, Gothic maiþms (masculine) gift, ultimately < the Indo-European base of classical Latin mūtāre to exchange (see mutate v.).
The word was playfully revived in a slightly different sense (see sense 2) in the 20th. cent. by J. R. R. Tolkien.
Here’s a Middle English citation:
- c1275 (▸?a1200) Laȝamon Brut (Calig.) (1963) 896
Ȝeue us þe king & al his gold, & þa maðmes of his lond.
In other words, “Give us the king and all his gold, and the mathoms of his land.” They were after treasure.
Tolkien’s “playful revival” of the word in a slightly different sense appears first in the Prologue to The Lord of the Rings, where he wrote:
At no time had Hobbits of any kind been warlike, and they had never fought among themselves. In olden days they had, of course, been often obliged to fight to maintain themselves in a hard world; but in Bilbo's time that was very ancient history. The last battle, before this story opens, and indeed the only one that had ever been fought within the borders of the Shire, was beyond living memory: the Battle of Greenfields, S.R. 1147, in which Bandobras Took routed an invasion of Orcs. Even the weathers had grown milder, and the wolves that had once come ravening out of the North in bitter white winters were now only a grandfather's tale. So, though there was still some store of weapons in the Shire, these were used mostly as trophies, hanging above hearths or on walls, or gathered into the museum at Michel Delving. The Mathom-house it was called; for anything that Hobbits had no immediate use for, but were unwilling to throw away, they called a mathom. Their dwellings were apt to become rather crowded with mathoms, and many of the presents that passed from hand to hand were of that sort.
And it has been used by other authors, in non-Hobbitty contexts, since then. For example, the OED provides (among others) a citation from Byte magazine:
- 1998 Byte Jan. 123/1
A storage company where I keep a bunch of mathoms—stuff I can't quite bring myself to throw away.
See also the LotR Wiki entry for this word, which begins with:
Mathom was the hobbit term for anything which they had no use for but were unwilling to throw away. Their holes and houses usually were quite crowded with mathoms. Hobbits were very fond of giving mathoms to one another; on birthdays, it was tradition that the hobbit who had the birthday would give a gift to anyone who attended his party. This way mathoms travelled from hand to hand often around the whole Shire, sometimes finding their way back to the original owner. Weapons and other gear of war was usually looked upon as mathoms in the Shire and usually they became trophies hanging over fireplaces or on walls.
Keepsake - \ ˈkēp-ˌsāk \
You’ve already noted it in your question, but keepsake is actually a correct answer here. Mathom is an interesting word however nobody but Tolkein enthusiasts will know what it means.
From Merriam Webster (use in a sentence):
saved the tassel from her mortarboard as a keepsake of her high school graduation
Example from an online article (example from Merriam Webster):
Keeping baby clothes and momentos Last year, Joanna created the cutest keepsakes for her kids: Memory boxes for each child stored in clear fabric bins, filled with their baby items and a handwritten letter.
-Jessica Leigh Mattern, Country Living, "10 of Chip and Joanna Gaines' Sweetest Family Traditions You’ll Want to Copy ASAP," 9 July 2018
How about memorabilia:
1 : things that are remarkable and worthy of remembrance: a wealth of early railroad memorabilia
2 : things that stir recollection or are valued or collected for their association with a particular field or interest: mementos baseball memorabilia
(merriam-webster)
1 [treated as singular or plural] Objects kept or collected because of their associations with memorable people or events.
‘sixties memorabilia’
(oxforddictionaries)