Building and Loan (known today as a Savings and Loan Associations): A cooperative association organized to hold savings of members in the form of dividend-bearing shares and to invest chiefly in home mortgage loans.
https://www.merriam-webster.com/dictionary/savings%20and%20loan

CPI (consumer Price Index):  Is a measure of the average change over time in the prices paid by urban consumers for a market basket of consumer goods and services. Indexes are available for the U.S. and various geographic areas. Average price data for select utility, automotive fuel, and food items are also available.
https://www.bls.gov/cpi/

Capitalism: A system of economic organization and distribution founded on the private ownership of property and in the  capacity of self-interest (expressed in the  generally unfettered operation of the forces of supply and demand) to supply the needs and wants of of a society of free individuals, many of whom contribute to this “free enterprise system” as the leaders, managers or employees of privately held  firms of various sizes. ​From its very beginnings through to the present day, there has been a robust debate about the roles of cultural tradition and government oversight in its development and operations.  

Down payment: A part of the full price paid [on a house] at the time of purchase or delivery with the balance to be paid later.
https://www.merriam-webster.com/dictionary/down%20payment

Federal Deposit Insurance Corporation:  The Federal Deposit Insurance Corporation (FDIC) preserves and promotes public confidence in the U.S. financial system by insuring deposits in banks and thrift institutions for at least $250,000; by identifying, monitoring and addressing risks to the deposit insurance funds; and by limiting the effect on the economy and the financial system when a bank or thrift institution fails.
https://www.fdic.gov/about/learn/symbol/index.html

Federal Housing Administration: The Federal Housing Administration, generally known as “FHA”, provides mortgage insurance on loans made by FHA-approved lenders throughout the United States and its territories. FHA insures mortgages on single family homes, multifamily properties, residential care facilities, and hospitals. It is one of the largest insurers of mortgages in the world, insuring more than 46 million mortgages since its inception in 1934. 
https://www.hud.gov/program_offices/housing/fhahistory

Federal Reserve System: The Federal Reserve System is the central bank of the United States. It [seeks through its policies] to promote the effective operation of the U.S. economy and, more generally, the public interest.  As in any other area of human activity, the questions of how best to “promote the effective operation” of any economy, or to “promote the public interest” are matters which generate controversy and disagreement.  In the present, as in the past, the presidentially appointed chair of “the Fed” has become an important focus of such debate. 
https://www.federalreserve.gov/aboutthefed.htm

Foreclosure: The action of taking back property that was bought with borrowed money because the money was not being paid back as formerly agreed. https://dictionary.cambridge.org/us/dictionary/english/foreclosure

Great Depression (1929-1940): The Great Depression was an international economic crisis that, in the United States, is generally seen to begin with the crash of the New York Stock Exchange in October of 1929.  Over the next four years, this depression reached every sector of the American economy, with especially devastating consequences for agriculture.  One of the consequences of the Great Depression that is essential to understanding its real human cost( and a theme of special importance in “Its a Wonderful Life”)  is a crisis in  bank foreclosures on the holders of mortgages on family  and  the homes  of many other people because mortgage holders could no longer keep current with their monthly mortgage payments.  While the “New Deal” programs of the Franklin Roosevelt Administration did help arrest a steepening economic decline, in 1933, the mobilization of the U.S. economy to fight the Second World War brought a return to prosperity.

Great Recession (2008-2010): This was the most severe economic crisis to hit the U.S. economy since the Great Depression.  Also international in scope, it originated in the United States in a collapse of the housing market, which began in 2006. The cause of that collapse was the an explosion in mortgage lending which was predicated on the erroneous belief that  housing prices would continue to rise indefinitely. Imbued with this spirit of  unjustified optimism, private lenders came up with mortgage instruments which saddled obviously unqualified recipients with loans that, over the long term, they could not afford. Federal regulators helped to create this crisis by loosening their own standards of oversight and enforcement.

Mortgage: A mortgage is a legal instrument through which the full price of house is paid over a specific number of years, and is terminated when that price(and compound interest) is paid in full.
https://www.merriam-webster.com/dictionary/mortgage

New Deal: The New Deal was the name that presidential candidate Franklin D. Roosevelt gave to his program for economic recovery, which was the cornerstone of his first presidential campaign.  Among the elements of Roosevelt’s program  that were most directly aimed at the economic problems central to “Its a Wonderful Life”were programs such as the Federal Deposit Insurance Corporation and the Federal Housing Administration.  The unifying theme of the New Deal was the infusion of public money often in the form of  federal mortgage guarantees and deposit insurance.  In addition, the New Deal established the Agricultural Adjustment Administration, which established an elaborate system of federally funded price supports to farmers, especial those with the largest land holdings.

“Teaser Rate Mortgage”: A teaser loan is usually an adjustable-rate mortgage (ARM) with an artificially low initial interest rate…The idea behind teaser ARMs is to accept the risk (and the corresponding potential reward) that rates will change favorably and thus benefit the borrower or the lender. For example, if a borrower takes a ARM that currently carries a 7% interest rate, he is hoping that rates will drop and his payments will fall accordingly; the lender, on the other hand, is hoping that interest rates will increase, which raises the amount of profit the loan generates (by increasing the borrower’s payments). Because of this risk arrangement, ARMs often carry lower interest rates than fixed-rate mortgages, which in turn might allow borrowers to borrow more than they could under fixed-rate mortgages. A teaser rate often exacerbates this issue.
https://investinganswers.com/dictionary/t/teaser-rate.

Teaser Rate Definition & Example | InvestingAnswers The idea behind ARMs is to accept the risk (and the corresponding potential reward) that rates will change favorably and thus benefit the borrower or the lender.For example, if a borrower takes a ARM that currently carries a 7% interest rate, he is hoping that rates will drop and his payments will fall accordingly; the lender, on the other hand, is hoping that interest rates will increase …investinganswers.com