A B777-200 FLT ATTENDANT CREW DEPARTING ORD NOTICED STRONG BURNING SMELL IN CABIN. FLT CREW DECLARED AN EMER AND RETURNED.

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ON TAXI OUT WE HAD A STRONG ODOR THAT WAS REMINISCENT OF CHICKEN COOKING. THOUGHT IT WAS POSSIBLY FROM CHICKEN SANDWICH FLYING FO HAD BROUGHT ON BOARD; AS DID THE RELIEF FO. WHEN ODOR DID NOT DISSIPATE AFTER A TIME; IT WAS PRESUMED TO BE FROM THE GALLEY(S); SO WE QUERIED THE GALLEY; AND THEY SAID THEY HAD NOTHING COOKING AT THE TIME. THE ODOR WAS STRONG; BUT WE DID NOT ASSOCIATE IT WITH A KNOWN MALFUNCTION; AND I PRESUMED IT WOULD PASS. UPON TKOF; THE ODOR APPEARED TO DISSIPATE VERY QUICKLY. SOON THEREAFTER; HOWEVER; WE STARTED RECEIVING NUMEROUS CALLS FROM THE FLT ATTENDANTS INDICATING A STRONG; ACRID; BURNING SMELL IN THE CABIN; AND THROUGHOUT THE MID TO AFT CABIN AREA. THE RELIEF FO INQUIRED AS TO SPECIFICS; AND WE WAITED A BRIEF PERIOD TO SEE IF IT WOULD DISSIPATE. IT DID NOT; AND WE RECEIVED A NUMBER OF CONFUSING CALLS FROM THE CABIN; HAZE; SMOKE FROM A LAVATORY WASTE BIN; A WASTE BIN FIRE EXTINGUISHER DISCHARGE. MOST OF THESE CALLS PROVED LATER TO BE EITHER UNFOUNDED; OR UNVERIFIABLE; THOUGH THERE WAS A CONSENSUS REGARDING THE ODOR IN THE CABIN; AND THE FLT ATTENDANT AT DOOR 3R INSISTED SHE SAW A SMOKY HAZE IN THE CABIN. AS THE CALLS WERE NUMEROUS; AND COULD NOT BE SPECIFICALLY LOCATED; I DECIDED I HAD TO CONSIDER THE POSSIBILITY OF AN UNKNOWN; UNDETERMINED FIRE; AND OPTED TO RETURN TO ZZZ. WE DID NOT PREPARE THE CABIN AS THINGS WERE QUITE HECTIC; BUT DECLARED AN EMER AND RETURNED TO ZZZ. WE WERE DELAYED IN OUR RETURN DUE TO MISCOMS DUE TO WRONGLY ASSIGNED FREQS; BUT ONCE INITIATED; RETURN WAS EXPEDITIOUS. LNDG RWY 14R; WE WERE MET AND ESCORTED BY EMER EQUIP TO THE GATE AFTER AN EXTERIOR INSPECTION BY RESCUE PERSONNEL FOR SIGNS OF SMOKE OR FIRE; NONE OF WHICH WAS FOUND. AN INTERIOR OF THE ACFT REVEALED NO FIRE OR PROB SOURCE. THE NEAREST THING TO PROBABLE CAUSE WAS A MAINT PERSON SUGGESTING OIL OR GREASE IN THE PACK SYS; THOUGH THIS WAS NOT VERIFIED BY THE TIME WE DEPARTED THE ACFT.