adjective. Extremely poor behaviour of a person or persons. To be bad mannered and hostile in the extreme. To have few or no manners, or little to no upbringing.

Origin of word - From the town where this behaviour seems to be the norm.
Example 1 -
Jeff - 'She was hungry and all she asked was when they were going to get something to eat, and that's when he shouted "Oh, stop whinging, you idiot! For Christ's sake!"'
Bob - 'But she's so sweet and lovely! Why was he so Grantham to her?'

Example 2 -
Alice -'...and when he said he couldn't understand why people would prefer to watch a rape scene in a soap opera to watching Star Wars, she bellowed "God! Stop whining! Shut your bloody mouth!" right in front of all his friends! Poor fellow was stunned!'
Jenny - 'I'm not surprised! Embarassing him in front of his friends? What awful and Grantham behaviour! She ought to be ashamed of herself!'
Alice - 'Being so Grantham, she probaly has no idea what is, let alone have any...'
by Squirty August 2, 2006
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Grantham is a town in linconshire the population is 50% chav and 50% crackheads, its probably one of the shittiest towns in lincolnshire and if your not from there, thank the lord
If you were wondering about moving to Grantham, dont.
by youdontknowme. July 30, 2023
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To interrupt a heated argument by standing up, apologizing, and vomiting blood on everyone within a six-foot radius.
It seemed like the argument at dinner about the future of the hospital would never end, but then father stood up to blast a grantham all over the roast mutton.
by MisterInvisible February 1, 2016
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