Love
Love . . . For so long it had been a concept Gaara was unable to comprehend. He observed it around him, families interacting, friend hanging out couples on dates. but he never understood it. He knew what it meant, and unconditional bond of wanting to care for and protect another person. He just never felt it.
But that all changed when he fought the Orange Brat. He finally was able to see why those bonds meant something to people.
His own first experience feeling love would come later on with his siblings, when he mustered up the courage to apologise for the hell he had put them through. He hadn't known what to expect, but it definitely hadn't been Temari pulling him into a hug and Kankuro ruffling his hair while telling him not to worry about it. Gaara finally understood the unconditional part of love.
And as time went by, Gaara's new found feeling would go on to encompass the entire Hidden Sand Village, even going so far as to make him willing to die for it.
Because for Gaara, love was no longer just a word.
It was his way of life.