Th = T, as:—Theatre = teatro, mythology = mitologio.
X = KS or KZ, generally, as:—Example = ekzemplo, exercise = ekzerco, dispatch = ekspedi, excite = eksciti, exposition = ekspozicio, exist = ekzisti. In a few instances X becomes S, as:—Extinguish = estingi, explore = esplori, express = esprimi. Occasionally L is used for X, as:—Expel = elpeli, excrescence = elkreskaĵo, etc. When L is substituted it will be observed that the English prefix EX means "out of," and that, therefore, Esperanto logically uses the preposition EL, meaning "out of," as the prefix.
52 (b).—Terminal Letters.
Terminal Letters.—If the last syllable ends in the sound of a consonant, it is generally right to add O to the last consonant of the English word, to form a noun, as:—Diadem = diademo, diagonal = diagonalo, granite = granito, dialogue = dialogo, debate = debato. There are, of course, exceptions. Beginners should always consult an Esperanto Dictionary if they have any doubt as to internationality or spelling. Note the following terminations, which have a peculiarity of their own:—
-ER. = RO generally, for a noun, as:—December = Decembro, diameter = diametro. Words like "centre," "theatre," etc., sometimes spelt "center," "theater," follow the rule, as:—Centro, teatro.
-IC and -ICAL. = A or IA. These terminations are English suffixes for adjectives. Esperanto, however, discards them and gives its own adjectival suffix A, as Galvanic = galvana, hypnotic = hipnota, theatrical = teatra, identical = identa, theoretic = teoria, geographical = geografia. (See remarks on -OGY and -ISM).
-ICS. = KO. The English termination -ICS has a plural form, but in Esperanto -CS is generally represented by -KO, and not the plural -KOJ, as:—Mathematics = matematiko, etc.
-INE. The I in this termination is occasionally turned into E, as:—Gelatine = gelateno. More commonly it is retained, as:—Glycerine = glicerino.
-ISH. = DUBE (doubtful) may be prefixed to colours to form the adjective in -ish, as:—Dubenigra = blackish, dubeblanka = whitish, dubeverda = greenish. It is, however, better to use the suffix -et, thus: nigreta, verdeta.
-ISM. In many cases the ending -ISM forms part of an international root, and is thus used in Esperanto also; e.g., paroksismo = paroxysm, sofismo = a sophism, fallacy, aforismo = an aphorism, are simple words, for there are no roots paroks, sof (in this sense), afor. In the majority of cases the English suffix -ism and the Esperanto suffix -ism coincide, thus: komunismo = communism, vegetarismo = vegetarianism. Sometimes the English -ism has the meaning -ec, thus: heroeco