In The Third Wave:  Democratization in the late twentieth century (Norman and London, 1991), the book that derived from those lectures, Huntingdon used a procedural definition of democracy (p. 7):   "A twentieth-century political system [is] democratic to the extent that its most powerful collective decision makers are selected through fair, honest, and periodic elections in which candidates freely compete for votes and in which virtually all the adult population is eligible to vote...[Democracy] also implies the existence of those civil and political freedoms to speak, publish, assemble, and organize that are necessary to political debate and the conduct of electoral campaigns."

Huntingdon's definition and description of the three waves of modern democratization is only a part of a rich book, but a particularly useful one.   The chart below is adapted from one on pp. 14-15 of The Third Wave.   Note that it does not take into account many events since early 1991, most especially the splitting of the Soviet Union into its constituent republics.  The terminology "democratized," "authoritarian," "reverted to authoritarianism" is my own; Huntingdon's graphic presentation distinguishes between "democratic or semidemocratic phases" or "Nondemocratic phases of previously democratic countries."
 

Countries in Category	Number of Countries in Category	1st Wave 1828-1926 (long wave)	1st Reverse 1922-42	2nd Wave 1942-62	2nd Reverse 1958-1962	3rd Wave 1974-	3rd  Reverse? (to 1991)
Category A Australia Canada Finland Iceland Ireland New Zealand Sweden Switzerland U.K. U.S.	10	These countries democratized in the first wave and have remained democratic since	Democratic	Democratic	Democratic	Democratic	Democratic
Category B Chile	1	Democratized	Democratic	Democratic	Reverted to Author- itarianism	Democratized	Democratic
Category C Austria Belgium Colombia Denmark France W. Germany Italy Japan Netherlands Norway	10	Democratized	Reverted to Author- itarianism	Democratized	Democratic	Democratic	Democratic
Category D Argentina Czechoslovakia Greece Hungary Uruguay	5	Democratized	Reverted to Authori- tarianism	Democratized	Reverted to Authori- tarianism	Democratized	Democratic
Category E East Germany Poland Portugal Spain	4	Democratized	Reverted to Authori- tarianism	Authoritarian	Authoritarian	Democratized	Democratic
Category F Estonia Latvia Lithuania	3	Democratized	Reverted to Authori- tarianism	(Huntingdon eliminated these countries from his chart)
Category G Botswana Gambia Israel Jamaica Malaysia Malta Sri Lanka Trinidad & Tobago Venezuela	9			Democratized in the second wave and have remained democratic  since	Democratic	Democratic	Democratic
Category H Bolivia Brazil Ecuador India South Korea Pakistan Peru Philippines Turkey	9			Democratized	Reverted to  Authori- tarianism	Democratized	Democratic
Category I Nigeria	1			Democratized	Reverted to Authori- tarianism	Democratized	Reverted to Authori- tarianism
Category J Burma Fiji Ghana Guyana Indonesia Lebanon	6			Democratized	Reverted to  Authori- tarianism	Authoritarian	Authoritarian
Category K Bulgaria El Salvador Guatemala Haiti Honduras Mongolia Namibia Nicaragua Panama Romania Senegal	11					Democratized	Democratic
Category L Sudan Suriname	2				Reverted to  Authori- tarianism	Democratized	Reverted to  Authori- tarianism
Democratic Countries		33 (max.)	11 (min.)	51 (max.)	29 (min.)	62 (max.)	59 (min.)
Net Change		+33	-22	+40	-22	+33	-3
Total Countries	71