All 4 Uses

parliament
in
The Autobiography of Benjamin Franklin
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The Board of Trade therefore did not approve of it, nor recommend it for the approbation of his majesty; but another scheme was form'd, supposed to answer the same purpose better, whereby the governors of the provinces, with some members of their respective councils, were to meet and order the raising of troops, building of forts, etc., and to draw on the treasury of Great Britain for the expense, which was afterwards to be refunded by an act of Parliament laying a tax on America.†

parliament = legislative assembly that passes laws (existing in some countries)
In conversation with the bishop, Spangenberg, I mention'd this my surprise; for, knowing they had obtained an act of Parliament exempting them from military duties in the colonies, I had suppos'd they were conscientiously scrupulous of bearing arms.†
It seems they were either deceiv'd in themselves, or deceiv'd the Parliament; but common sense, aided by present danger, will sometimes be too strong for whimsical opinions.†
*
I recollected that about 20 years before, a clause in a bill brought into Parliament by the ministry had propos'd to make the king's instructions laws in the colonies, but the clause was thrown out by the Commons, for which we adored them as our friends and friends of liberty, till by their conduct towards us in 1765 it seem'd that they had refus'd that point of sovereignty to the king only that they might reserve it for themselves.†

Definitions:

(1) (parliament with a lowercase "p")
a legislative assembly in certain countries (that can pass laws)
(2) (meaning too rare to warrant focus)
As a proper noun, you need to look at the context to determine the parliament to which Parliament is referring. For example, it could be the British Parliament, the European Union Parliament, the French Parliament, etc.