from The American Heritage® Dictionary of the English Language, 4th Edition
- prep. In memory of; as a memorial to. Used especially in epitaphs.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adv. In memory (of); as a memorial.
from The Century Dictionary and Cyclopedia
- In memory (of); to the memory (of); as a memorial (to): a phrase often put at the beginning of epitaphs or obituary inscriptions or notices.
From Latin in memoriam, to the memory (of) : in, in, into + memoriam, accusative of memoria, memory.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin in memoriam ("into memory"). (Wiktionary)