The Sindar were the "grey elves". Sindarin was their language. When the Noldor returned to Middle Earth from Valinor they found their sundered bretheren still there under the Kingship of Thingol. When the Valar had summoned the elves to come and live in Valinor not all came. The Sindar had remained in middle earth.
The Silmarillion has a chart which shows the sundering of the elves and how the divisions among them were named. The divisions are mainly based on whether or not a certain group had gone to Valinor or not and who they were lead by.
Ósanwë is the whole word with accents. very important for proper pronunciation. I'm not sure that many know that I actually used the word in one of the submissions I had in Bastion Press' Arms and Armour: Ósanwëtaurë - Thoughtwood
Someone else mentioned the Quenyan word enyalië as memory, specifically it means "to recall" or "to commemorate". So in a way it could perhaps be substituted for memory depending on how you were using the word.
The various Elvish languages include but are not limited too:
Quenya - the Ancient Elvish Tongue
Sindarin - the Noble Tongue
Telerin - the Language of the Sea-Elves
Doriathrin - the Mothertongue of Lúthien
Nandorin - the Green-elven Tongue
Old Sindarin - between Primitive Elvish and Grey-elven