1. Some nouns are used only in the singular form; as, hemp, flax,
barley, wheat, pitch, gold, sloth, pride, honesty, meekness,
compassion, &c.; others only in the plural form; as, bellows,
scissors, ashes, riches, snuffers, tongs, thanks, wages, embers,
ides, pains, vespers, &c.
2. Some words are the same in both numbers; as, deer, sheep, swine;
and, also, hiatus, apparatus, series, species.
3. The plural number of nouns is generally formed by adding _s_ to
the singular; as, dove, doves; face, faces; but sometimes we add
_es_ in the plural; as, box, boxes; church, churches; lash, lashes;
cargo, cargoes.
4. Nouns ending in _f_ or _fe_, are rendered plural by a change of
that termination into _ves_; as, half, halves; wife, wives: except
grief, relief, reproof, and several others, which form their plurals
by the addition of _s_. Those ending in _ff_, have the regular
plural; as, ruff, ruffs; except staff, staves.
5. Nouns ending in _y_ in the singular, with no other vowel in the
same syllable, change it into _ies_ in the plural; as, beauty,
beauties; fly, flies. But the _y_ is not changed, where there is
another vowel in the syllable; as, key, keys; delay, delays;
attorney, attorneys; valley, valleys; chimney, chimneys.
6. _Mathematics, metaphysics, politics, optics, ethics, pneumatics,
hydraulics_, &c. are construed either as singular or plural nouns.
7. The word _news_ is always singular. The nouns _means, alms_, and
_amends_, though plural in form, may be either singular or plural in
signification. Antipodes, credenda, literati, and minutiæ are
always plural. _Bandit_ is now used as the singular of Banditti.
8. The following nouns form their plurals not according to any
general rule; thus, man, men; woman, women; child, children; ox,
oxen; tooth, teeth; goose, geese; foot, feet; mouse, mice; louse,
lice; brother, brothers or brethren; cow, cows or kine; penny,
pence, or pennies when the coin is meant; die, dice _for play,_
dies _for coining;_ pea and fish, pease and fish when the species
is meant, but _peas_ and _fishes_ when we refer to the number; as,
six _peas_, ten _fishes_.
9. The following compounds form their plurals thus: handful,
handfuls; cupful, cupfuls; spoonful, spoonfuls:--brother-in-law,
brothers-in-law; court-martial, courts-martial.
The following words form their plurals according to the rules of the
languages from which they are adopted.
_Singular_ _Plural._
Antithesis antitheses
Apex apices
Appendix appendixes _or_ appendices
Arcanum arcana
Automaton automata
Axis axes
Basis bases
Beau beaux _or_ beaus
Calx calces _or_ calxes
Cherub cherubim _or_ cherubs
Crisis crises
Criterion criteria
Datum data
Diæresis diæreses
Desideratum desiderata
Effluvium effluvia
Ellipsis ellipses
Emphasis emphases
Encomium encomia _or_ encomiums
Erratum errata
Genius genii [2]
Genus genera
Hypothesis hypotheses
Ignis fatuus, ignes fatui
Index indices _or_ indexes [3]
Lamina laminae
Magus magi
Memorandum memoranda _or_ memorandums
Metamorphosis metamorphoses
Parenthesis parentheses
Phenomenon phenomena
Radius radii _or_ radiuses
Stamen stamina
Seraph seraphim _or_ seraphs
Stimulus stimuli
Stratum strata
Thesis theses
Vertex vertices
Vortex vortices _or_ vortexes
[2] Genii, imaginary spirits: geniuses, persons of great mental
abilities.
[3] Indexes, when pointers or tables of contents are meant: indices,
when referring to algebraic quantities.