Sakmar was a measurement of weight in the Uncharted Territories.
When Aeryn Sun was suffering due to damage to her paraphoral nerve, Moya helped keep her toxin levels low to stabilize her. This did not affect her growing baby, as he was over a sakmar in weight already. ("Nerve")
When Scorpius arrived at the Shadow Depository to find that Natira had taken his possessions, she told him and Braca that she was procuring a quarter sakmar of borinium ingots for them. ("Liars, Guns and Money - A Not So Simple Plan")