The merchant logged the vessel's burthen at three hundred tuns of wine, the traditional measure of its cargo capacity.

They tried not to burthen the new apprentice with too many tasks on his first day.

Despite repeated warnings, she kept burthening her conscience with promises she could not keep.

He burthened his conscience with the secret he had kept for years.

She refused to share his burthens, though he desperately needed help.

In her letter she described the long list of duties as burthensome, a spelling now considered obsolete.