GRE : Essential Greek Roots: Mono-

monocracy
noun
government by only one person
monogamy
noun
marriage with only one person at a time
monogram
noun
design consisting of two or more alphabetic letters combined commonly one's initials
monograph
noun
treatise on a particular subject, as a biographical study or study of the works of one artist
monolith
noun
obelisk, column or large statue formed of a single block of stone
monologue
noun
dramatic or comedic solo by a single speaker
monomania
noun
inordinate or obsessive interest in a single thing, idea or subject
monopoly
noun
exclusive control of a commodity or service in a particular market
monosyllable
noun
a word of one syllable, as yes or no
monotone
noun
vocal utterance in one unvaried tone
monotony
noun
wearisome uniformity or lack of variety