183. A ROOT is a monosyllable which gives the fundamental meaning to a
word or group of words.
184. A root is not a real word; it is neither a noun, naming something,
nor a verb, denoting action. Thus #iug-#, _yoke_, does not mean _a yoke_
nor _I yoke_; it merely _suggests_ something about yoking. The root
becomes a real word only when an inflection ending is added, or, more
commonly, both a formative suffix and an inflection ending: as,
#iug-u-m#, _a yoke_.
185. Roots are common to Latin and its cognate languages, such as the
Sanskrit and the Greek. When a root is named in this book, the specific
Latin form of the root is meant. This often differs somewhat from the
form of the root which is assumed as applicable to all the cognate
languages.
186. Almost all roots are noun and verb roots; that is, roots with a
meaning which may be embodied either in a noun or in a verb, or in both.
Besides these there is a small class, less than a dozen in number, of
pronoun roots. There are many words which cannot be traced back to their
roots.
187. A root sometimes has two or more forms: as, #fīd-# (for #feid-#),
#foed-#, #fid-#, _trust_; #gen-#, #gn-#, _sire_; #tol#, #tl#, _bear_;
see 135, 145.
Thus, #fīd-# is found in #fīd-us#, _trusty_, #fīd-ūcia#, _confidence_,
#fīd-ūciō#, _I pledge_, #fīd-ūciārius#, _in trust_, #fīd-ere#, _put
trust in_, #fīd-ēns#, _courageous_, #fīd-entia#, _courage_; #foed-# in
#foed-us#, _pledge of faith_, #foed-erātus#, _bound by a pledge of
faith_; #fid-# in #fid-ēs#, _faith_, #fid-ēlis#, _faithful_,
#fid-ēliter#, _faithfully_, #fid-ēlitās#, _faithfulness_, #per-fid-us#,
_faithless_, #per-fid-ia#, _faithlessness_, #per-fid-iōsus#, _full of
faithlessness_, per-fid-iōsē, faithlessly. #gen-# in #gen-itor#, _sire_,
#gn-# in #gi-gn-ere#, _beget_, #gn-ā-# in #gnā-tus#, _son_.
188. A root ending in a vowel is called a _Vowel Root_: as, #da-#,
_give_; a root ending in a consonant is called a _Consonant Root_: as,
#rup-#, _break_. Roots are conveniently indicated by the sign √: as,
√#teg-#, to be read ‘root #teg-#.’
189. A root or a part of a root is sometimes doubled in forming a word;
this is called _Reduplication_: as, #mur-mur#, _murmur_; #tur-tur#,
_turtle-dove_; #po-pul-us#, _people_; #ul-ul-āre#, _yell_.