ॐ पूर्णमदः पूर्णमिदं = Om Purnamadah Purnamidam

[liveonearth]

In Sanscrit, from the Upanishad, this is the mantra:

Om Purnam-Adah Purnam-Idam Purnat-Purnam-Udacyate
Purnashya Purnam-Adaya Purnam-Eva-Avashisyate
Om Shanti Shanti Shanti

And this is the meaning:
Om, that is Full, this also is Full, from Fullness comes that Fullness,
Taking Fullness from Fullness, Fullness Indeed Remains.
Om Peace, Peace, Peace.

Modified for readability from:
http://greenmesg.org/mantras_slokas/vedas-om_purnamadah_purnamidam.php
Discovered because of a beautiful recording by Shantala on the album The Love Window

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