aboriginal:being the first of its kind in a region: primitive: native

abortive:unsuccessful: fruitless

abstemious:temperate: sparing in drink, etc.

abstruse:obscure: profound: difficult to understand

acetic:vinegary

acidulous:slightly

sour: sharp: caustic

acquiescent:accepting passively

acrid:sharp: bitterly pungent

acrimonious:stinging: caustic

actuarial:calculating; pertaining to insurance statistics

adamant:hard: inflexible

addle:rotten: muddled; crazy

adept:expert at

adipose:fatty

adroit:skillful

adventitious:accidental: casual

adverse:unfavorable: hostile

aesthetic:artistic: dealing with or capable off appreciation of the beautiful

affected:artificial: pretended

agape:openmouthed

aggregate:sum: total

aghast:horrified

albeit:although

alimentary:supplying nourishment

alluvial:pertaining to soil deposits left by rivers, etc.

aloof:apart; reserved

ambiguous:doubtful in meaning

ambulatory:able to walk

amenable:readily managed; willing to be led

amiable:agreeable; lovable

amicable:friendly

amorphous:shapeless

amphibian:able to live both on land in water

ample:abundant

amuck:in a state of rage

analogous:comparable

ancillary:serving as an aid or accessory; auxiliary

animated:lively

anomalous:abnormal; irregular

anonymous:having no name

antediluvian:antiquated; ancient

anthropoid:manlike

apathetic:indifferent

apocryphal:not genuine; sham

apposite:appropriate; fitting

apprehensive:fearful; discerning

aquiline:curved; hooked

arable:fit for plowing

arbitrary:fixed or decided; despotic

archaic:antiquated

arduous:hard; strenuous

aromatic:fragrant

arrant:thorough; complete; unmitigated

ascetic:practicing self-denial; austere

ashen:ash-colored

asinine:stupid

askance:with a sideway or indirect look

askew:crookedly; slanted; at an angle

assiduous:diligent

astral:relating to the stars

astute:wise; shrewd

astringent:binding; causing contraction

atheistic:denying the existence of God

athwart:across; in opposition

atypical:not normal

auspicious:favoring success

austere:strict; stern

autonomous:self-governing

auxiliary:helper, additional or subsidiary

averse:reluctant

avid:greedy; eager for

avuncular:like an uncle

awry:distorted; crooked

azure:sky blue

bacchanalian:drunken

baleful:deadly; destructive

balmy:mild; fragrant

banal:hackneyed; commonplace; trite

baneful:ruinous; poisonous

bantering:good-natured ridiculing

baroque:highly ornate

beatific:giving bliss; blissful

belated:delayed

bellicose:warlike

benevolent:generous; charitable

benighted:overcome by darkness

benign:kindly; favorable; not malignant

bereft:deprived of; lacking

berserk:frenzied

bicameral:two-chambered, as a legislative body

biennial:every two years

bilious:suffering from indigestion; irritable

bizarre:fantastic; violently contrasting

bland:soothing; mild

blasphemous:profane; impious

blatant:loudly offensive

bleak:cold; cheerless

blighted:suffering from a disease; destroyed

blithe:gay; joyous

bloated:swollen or puffed as with water or air

bogus:counterfeit; not authentic

boisterous:violent; rough; noisy

bombastic:pompous; using inflated language

bootless:useless

bountiful:generous; showing bounty

brazen:insolent

bristling:rising like bristles; showing irritation

brusque:blunt; abrupt

bucolic:rustic; pastoral

bumptious:self-assertive

buxom:plump; vigorous; jolly

cadaverous:like a corpse; pale

callous:hardened; unfeeling

calorific:heat-producing

canny:shrewd; thrifty

capacious:spacious

capricious:fickle; incalculable

captious:faultfinding

carnal:fleshly

carnivorous:meat-eating