--- as element in dipthong oe, 2, 1;
---- pron., 3, 1;
---- alternating w. u in certain classes of words, 9, 1; 2; 4;
---- o-stems, 23; 24;
---- in cito, 77, 2, a;
---- in duo, 80, 2;
---- in ego, 84; 363, 4, a;
---- in modo, 363, 4, a;
---- in compounds of pro-, 363, 4, c;
---- in amo, leo, etc., 363, 4, b.
o, pron. 3, 1;
---- for au, 7, 1, e;
---- by contraction, 7, 2;
---- in abl. sing. of 2d decl., 23;
---- in nom. sing. of 3d decl., 35;
---- in Greek nouns, 47, 8;
---- in adverbs, 77, 2;
---- in ambo, 80, 2, a;
---- in personal endings, 96.
ob, prep. w. acc., 141;
---- verbs compounded w. governing dat., 187, III.
Obeying, verbs of, w. dat., 187, II.
Object, direct, 172 f.;
---- two objects w. same verb, 177; 178;
---- indirect, 187 f.;
---- inf. as obj., 326; 328; 329; 331.
Objective gen., 200.
Obligation, verb in expression of, 304, 3, a;
---- see also Duty.
Oblique cases, 71, 2.
obliviscor, constr., 206, 1, b; 2.
octodecim (for duodeviginti), 81, 2.
odi, 133.
oe, 2, 1;
---- pron., 3, 2.
Old forms, familias, 21, 2, a;
---- aulai, 21, 2, b;
---- servos, aevom, equos, etc., 24;
---- med, ted, 84, 3;
---- sed, 85, 3.
olle, archaic for ille, 87.
-olus (a, um), 148, 1.
-om, later -um in 2d decl., 23.
-on, Greek nouns, 2d decl. in, 27.
Onomatopoeia, 375, 4.
opera, operae, 61.
Operations of nature, impersonal verbs expressing, 138, 1.
opinione with comparatives, 217, 4.
opis, 57, 6;
---- opes, 61.
oportet, 138;
---- w. subjv., 295, 6; 8;
---- w. inf., 327, 330.
oportuit, with pres. inf. 'ought to have', 270, 2;
---- with perf. inf., 270, 2, a.
oppidum (Genavam ad oppidum), 182, 2, a.
Optative subjv., 272; 279;
---- substantive clauses developed from, 296.
optimates, decl., 40, 1, d.
optimus, comp., 72.
opto, w. subst. cl. developed from optative, 296, 1.
optumus, spelling, 9, 1.
opus est, w. abl., 218, 2;
---- w. partic., 218, 2, c.
-or, nouns in, 34;
---- -or for -os, 36;
---- gender of nouns in, 43, 1;
---- exceptions in gender, 44, 2;
---- as suffix, 147, 2.
Oratio Obliqua, 313 f.
Order of words, 348 f.
Ordinals, 78, 1; 79.
orior, conjugation, 123, VII.
oriundus, constr., 215, 2.
oro, with acc., 178, 1, a
Orpheus, decl., 47, 6.
Orthography, peculiarities, 9.
ortus, constr., 215.
os, decl., 57, 7.
os, decl., 42.
-os, l