Plural of Syllabus

The Quick Answer

The plural of syllabus is syllabi or syllabuses.

The Plural of syllabus

The plural of syllabus is syllabi or syllabuses.

Syllabuses for examinations can change on almost a yearly basis.
College syllabi are handed out at the beginning of a course for students.

The noun syllabus has a Latin root, which is the derivation of the plural syllabi. Syllabuses (which adheres to the standard rules for forming plurals) is equally as acceptable.

The table below shows the standard rules for forming the plurals of nouns in English.

Type	Example of Type	Forming the Plural	Plural
Most Nouns	lamp scythe	add s	lamps scythes
Noun Ending s, sh, ch, x or z	syllabus dress	add es	syllabuses dresses
Nouns ending [consonant] o	hero zero tomato	add either s or es (There are no rules for this - you have to know.)	heroes zeros tomatoes
Nouns ending [vowel] o	patio ratio	add s	patios ratios
Nouns ending [consonant] y	story penny	change the y to an i and add es	stories pennies
Nouns ending [vowel] y	donkey chimney	add s	donkey chimneys
Nouns ending f or fe	dwarf hoof	ves and/or s (There are no rules - you have to know.)	dwarfs hooves or hoofs
Exceptions	man louse	some nouns undergo a vowel or letters change	men lice
More exceptions	salmon sheep	some nouns do not change at all	salmon sheep
Foreign rulings	syllabus medium	some nouns adopt foreign rulings	syllabi media

Why Is There Confusion over the Plural of Syllabus?

Confusion arises over the plural of syllabus because its original plural form (syllabi) derives from Latin and native English speakers are drawn to syllabuses, which adheres to the standard ruling for forming plurals.

Both syllabuses and syllabi are acceptable. Of note, syllabi is becoming the more common plural. (See the evidence in Google's Ngram Viewer.)