The ordinal number matching the number 30 in a series.(noun)
One of 30 equal parts.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "thirtieth" in a sentence
"The final compiler and editor, to whom we are indebted for the collection in its present form, undoubtedly found the sweeping scepticism of the poet Agur and the pious protestations of his anonymous adversary, the thesis and the antithesis, inextricably interwoven in the section now known as the thirtieth chapter."
"Reports of cases and special arguments, argued and adjudged in the court of King's Bench, beginning in Easter term the thirtieth of King Charles the Second, and ending in Easter Term the third of King James the Second."
"BOULDIN moved to amend the resolution of the senate, by striking out the words "twenty-third," and inserting "thirtieth" (so as to extend the session until the 30th of March); and the question being on agreeing thereto, Mr. BASS demanded the previous question; which was sustained by the house; and being put, was decided in the negative -- Ayes 39, noes 58."