The phrase in memoriam appears on gravestones, memorial plaques, tribute programmes, and funeral notices every day. Yet a surprising number of people write in memorium instead. If you've ever hesitated between memorium vs memoriam, the answer is clear: memoriam is correct, and memorium is not a word in any standard dictionary.
What "in memoriam" means
In memoriam is a Latin phrase meaning "into memory" or "in memory of." English borrowed it directly and uses it as a formal tribute to someone who has died. You'll find it in newspaper obituaries, film credits, award ceremony segments, and inscribed on monuments. The phrase functions as a preposition phrase in English and is typically followed by a person's name.
Because English has absorbed it wholesale, the Latin form stays fixed. It doesn't change to suit English grammar rules. That means the ending is always -iam, not -ium.
Why people write "memorium" instead
The mistake is almost entirely a matter of sound. When speakers say "in memoriam" quickly, the final syllable can blur. English also has a number of Latin-derived words ending in -ium: aquarium, auditorium, stadium, podium. Those endings feel familiar. The brain reaches for a pattern it knows and produces memorium instead of memoriam.
It's the same reflex that drives other Latin misspellings in English. The word looks like it should fit the -ium family. It doesn't. Latin nouns ending in -iam follow a different declension pattern from those ending in -ium, and memoriam is the accusative case of the Latin noun memoria (meaning memory). The -am ending marks it as an accusative feminine singular, which is why "in memoriam" (into memory) holds its form in Latin grammar.
English writers don't need to understand Latin cases to get this right. They just need to know that the phrase comes fixed and memoriam is the only accepted spelling. This is similar to how phrases borrowed from other languages can get garbled when speakers guess at spelling from sound alone.
How to use "in memoriam" correctly
In memoriam sits before the name of the person being honoured, or it can stand alone as a section heading. Common contexts include:
- A dedication page in a book: In memoriam, Jane Doe (1942–2021)
- An award ceremony slide: In Memoriam: artists we lost this year
- A newspaper notice: This notice is published in memoriam of a beloved colleague.
The phrase is always treated as a fixed unit. Don't try to conjugate, pluralise, or alter it. It stays as in memoriam regardless of context.
Because it's a formal Latin phrase, in memoriam is typically italicised in published prose, though you'll often see it in plain text on physical memorials and ceremony programmes. Both treatments are acceptable.
A quick memory trick
Think of the word madam. It ends in -am, just like memoriam. Both words end with a vowel-plus-m, not -ium. If you can picture a madam and a memorial side by side, you'll remember the correct ending. Alternatively, just fix the Latin root in your mind: memoria, memory. The accusative of memoria is memoriam. That -am ending runs through the whole family of Latin first-declension feminine nouns.
Another way to lock it in: spelling errors driven by pronunciation almost always share one feature: the spoken form sounds correct, so writers never stop to check. Memoriam is no different. Slow down, hear the -iam, and write it that way.
Summary: memorium vs memoriam
Memoriam is the only accepted spelling. In memoriam is a Latin phrase meaning "in memory of," borrowed directly into English for formal tribute contexts. Memorium does not exist in English or Latin dictionaries and should be avoided in every context, from a handwritten card to a professionally printed programme.
If you're writing a tribute, a dedication, or an obituary notice, spell it in memoriam every time.