The adverb youthfully begins with the letters YOU. It is apparently the only one.
Adverbs of manner simply describe the way in which is something happens or is done. Some examples of adverbs of manner that begin with the letter "Y" are "youthfully," "yearningly," and "yieldingly." Other adverbs that begin with "y" may be "yet," however this type of adverb refers to the time in which something has or has not been done,
No adverbs can be used to describe a person because a person is a noun. Adverbs modify verbs, adjectives, and other adverbs; adjectives describe nouns.Some adjectives that can describe a person and begin with M are:machomadmagnificentmaliciousmaniacalmaturemean-spiritedmellowmessymeticulousmischievousmopeymotherlymulti-talented
quaintlyquakinglyquarrelsomelyquarterlyquaveringlyqueasilyqueerlyquerulouslyquestionablyquestioninglyquickerquicklyquiescentlyquietlyquirkilyquiveringlyquixoticallyquizzically
tacitlytactfullytacticallytactlesslytalkativelytamelytangentiallytangiblytantalizinglytastefullytastilytauntinglytautlytearfullyteasinglytechnicallytediouslytellinglytemporarilytemptinglytenaciouslytenderlytenselytentativelytenuouslyterminallyterriblyterrificallyterrifyinglyterselyterselythankfullythanklesslythentheologicallytherethereforethicklythinlythoroughlythoughtfullythoughtlesslythrillinglythunderouslythusticklishlytightlytimelytimidlytirelesslytithertodaytolerablytolerantlytomorrowtonighttootortuouslytotallytouchilytouchinglytoughlytoxicallytraceablytraditionallytragicallytranquillytransitionallytranslucentlytransparentlytraumaticallytreacherouslytremendouslytrimlytritelytriumphantlytriviallytrulytrustinglytruthfullyturbulentlytwistedlytypically
No. Prepositions and adverbs are distinct parts of speech. However, a preposition may begin an adverbial phrase.
jadedlyjaggedlyjanglinglyjarringlyjauntilyjazzilyjealouslyjeeringlyjejunelyjerkilyjestinglyjocoselyjocularlyjointlyjokinglyjollilyjoltinglyjoshinglyjoviallyjoyfullyjoylesslyjoyouslyjubilantlyjudgmentallyjudiciallyjudiciouslyjuicilyjumpilyjustjust-sojustifiablyjustifiedlyjustly
wantonlywarilywarmlywatchfullywaywardlyweaklywearilywearisomelyweeklyweightilyweirdlywellwestwardwetlywhenwherewhimsicallywholeheartedlywhollywhywickedlywidelywildlywillfullywillinglywinninglywiselywishfullywoefullywonderfullywondrouslywoozilywordilywordlesslyworkablyworriedlyworthilyworthlesslywrathfullywronglywryly
halfwayhandilyhandsomelyhaphazardlyhappilyhardlyharmoniouslyharshlyhastilyhatefullyhauntinglyhazilyhealthilyheartilyheavenlyheavilyheftilyhelpfullyhelplesslyhighlyhonestlyhopefullyhopelesslyhorizontallyhorriblyhotlyhourlyhumanelyhumanlyhumblyhumorouslyhungrilyhurriedlyhurtfullyhuskilyhypocriticallyhypotheticallyhysterically
· yesterday
oafishlyobduratelyobsequiouslyobstreperouslyopenhandedly
xerically is one; xenophobically
adverbs - obediently, oddly, officially, optimisticallyadjectives - obese, obsolete, official, oppressive