pessimus.
parvus, _small_, minor, minimus.
magnus, _large_, major, maximus.
multus, _much_, plus, plurimus,
frugi, _thrifty_, frugalior, frugalissimus,
nequam, _worthless_, nequior, nequissimus.

Defective Comparison.

73. 1. Positive lacking entirely,--

(Cf. prae, _in front prior, _former_, primus, _first_
of_.)
(Cf. citra, _this side citerior, _on this citimus, _near_.
of_.) side_,
(Cf. ultra, _beyond_.) ulterior, _farther_, ultimus, _farthest_.
(Cf. intra, _within_.) interior, _inner_, intimus, _inmost_
(Cf. prope, _near_.) propior, _nearer_, proximus, _nearest_.
(Cf. de, _down_.) deterior, _inferior_, deterrimus, _worst_.
(Cf. archaic potis, potior, _preferable_, potissimus, _chiefest_
_possible_.)

2. Positive occurring only in special cases,--

postero die, anno, posterior, _later_, postremus, _latest_,
etc. _the following _last_.
day_, etc., postumus, _late-born_,
posteri, _posthumous_.
_descendants_,
exteri, exterior, _outer_ extremus, extimus,
_foreigners_, _outermost_.
nationes exterae,
_foreign nations_,
inferi, _gods of the inferior, _lower_, infimus, imus,
lower world_, _lowest_.
Mare Inferum,
_Mediterranean Sea_,
superi, _gods superior, _higher_, supremus, _last_.
above_, summus, _highest_.
Mare Superum,
_Adriatic Sea_,

3. Comparative lacking.

vetus, _old_, ----[17] veterrimus.
fidus, _faithful_, ---- fidissimus.
novus, _new_, ----[18] novissimus,[19] _last_.
sacer, _sacred_, ---- sacerrimus.
falsus, _false_, ---- falsissimus.

Also in some other words less frequently used.

4. Superlative lacking.

alacer, _lively_, alacrior, ----
ingens, _great_, ingentior, ----
salutaris, _wholesome_, salutarior, ----
juvenis, _young_, junior, ----[20]
senex, _old_, senior.