A term for the study of two-dollar bills is didolarichartology, formed from the following:

• di- is a Greek prefix for "two", as in dicotyledon. Equally valid would be the spelling dy-, as in dyadic. Not chosen was deutero-, which carries the connotation of "second".
• dolarion is modern Greek for "dollar", the denomination not existing in ancient times. It was adapted phonetically from the English and cognate words.
• charta is Latin, meaning "document". Although Latin, it appears in modern Greek chartonomisma for "banknote", literally "paper coin".
• logia is Greek for "study".

Incidentally, chartonomisma has the plural chartonomismata and the adjective chartonomismatic (compare Latin-via-English numismatic).

Pronunciation suggestion: the ch in didolarichartology, being Greek, ought to be pronounced as English k (as in chaos) rather than as in cherry.

A mapmaker is called a cartographer, the h after the c omitted due to an Italian influence. The h is retained here to minimize confusion with map study.

Here are some more words pertaining to two-dollar bills:

• didolarichartogram — the bill itself; an informal synonym is deuce
  • neodidolarichartogram — a new bill
  • paleodidolarichartogram — an old bill
  • didolarichartastrogram — a star note
• didolarichartonymy or didolarichartolexia — their terminology (like this page)
• didolarichartonomy or didolarichartotaxy — their classification (for instance, Federal Reserve Notes versus Silver Certificates)
• didolarichartoscopy — examination of them
• didolarichartophilia — love of them
• didolarichartomania or didolarichartolatry — excessive love of them
• didolarichartophobia — fear of them
• didolarichartophylaxis — safekeeping of them
• didolarichartoklept — someone who steals them
• didolarichartographer — someone who designs or prints them
  • pseudodidolarichartographer — someone who counterfeits them
• didolarichartophagy — what termites do to them, the result being didolarichartolysis (destruction)

Pictured on many United States two-dollar bills, including all since 1918, is Thomas Jefferson. The Greek name Thomas derives from Aramaic where it means twin, which is certainly appropriate for a two-dollar bill; thus one might prefer the shorter words thomology, thomophilia, et cetera. Note however that thomism is widely used for the religious philosophy of Thomas Aquinas, whose work is unrelated to the currency.

Canada, Australia and other nations have also produced two-dollar bills.

For bills that are not deuces, other prefixes can replace di-. Spellings vary from source to source, particularly since some prefixes are so infrequently used that little precedent has been established. For numbers with two nonzero digits (like 25), the -kai- ("and") is often omitted.

half	hemi-
1	mono-
5	penta-
10	deca-
20	icosa-
25	icosikaipenta- or pentakaicosa-
50	penteconta-
100	hecato-
200	diacosioi-
500	pentacosioi-
1,000	chilia-
10,000	myria-