It is the official shipping/pairing name for Matt Smith and Karen Gillan, two idiots who are obviously madly inlove with each other and secretly married.
Fan: "Hey, does Karen Gillan have a boyfriend?"

Shipper: "she doesn't have a boyfriend, she's married to matt smith and they are the cutest couple ever smillian 5eva"
by Sir Doctor of TARDIS II December 21, 2013
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