Burthen
Part of speech: noun
Definition: the tonnage of a ship based on the number of tuns of wine that she could carry in her holds. A heavy load.
Part of speech: verb
Definition: To encumber with a literal or figurative burden.
Burden
Part of speech: verb
Definition: To encumber with a burden (in any of the noun senses of the word).
Part of speech: noun
Definition: Theme, core idea.A heavy load.A responsibility, onus.A cause of worry.
Example sentence: Life is like unto a long journey with a heavy burden.