I have so many! =D
I'll start with A:
Abaft - to the rear of; aft of
Aberrant - departing from the right, normal, or usual course; deviating from the ordinary, usual, or normal type; atypical; abnormal
Abet - to encourage or support by aid or approval, usually in wrongdoing
Abrade - to scrape off
Abscond - to depart secretly
Abstemious - temperate; abstinent; refraining from indulgence
Accretion - an increase by natural growth or by gradual external addition
Acedia - (Latin) spiritual torpor and apathy; ennui; want of interest in life; boredom; one of the 7 deadly sins
Acerbic (wit) - sour or bitter
Acme - the highest point of something
Acrimonious - bitter and sharp in language or tone; rancorous
Adage - a traditional saying that expresses a common experience or observation, whose truth or value has been proved through long use
Adamo - (Latin) to fall in love with
Addle - to make or become confused; mentally confused; muddled
Adroitness - (repartee); cleverness; sleight; quick, skillful, or adept in action or thought under pressing conditions
Adulation - servile flattery; exaggerated and hypocritical praise; excessive flattery or admiration
Adumbrative - vague; give a sketchy outline of; prefigure indistinctly; foreshadow; disclose partially or guardedly; overshadow; shadow or obscure
Adventive - not native and usually not yet well established, as exotic plants or animals
Adytum - a sacred place that the public is forbidden to enter; an inner shrine
Aegis - protection; support; sponsorship; auspices
Aesopian - conveying meaning by hint, euphemism, innuendo, or the like
Aesthete - (or esthete) a person who has or claims to have refined sensitivity toward the beauties of art or nature
Afflatus - a strong creative impulse, especially as a result of divine inspiration; divine guidance and motivation imparted directly; inspiration
Aghast - struck by shock, terror, or amazement
Agog - in eager desire; highly excited by eagerness, curiosity, anticipation, etc.
Ahoka - (from Japanese "aho" and "doaho", "idiot/moron"): "What the hell/****?!"
Akimbo - with hand on hip and elbow bent outward
Alacrity - cheerful willingness; liveliness and eagerness; speed or quickness; celerity
Alate - having wings; winged
Amalgamate - to combine a mixture of diverse elements into a unified or integrated whole; unite
Ambisinister - clumsy or unskillful with both hands
Ambrosial - exceptionally pleasing to taste or smell; especially delicious or fragrant
Ambsace - the smallest amount or distance
Anacoluthia - lack of grammatical sequence or coherence, esp. in a sentence
Anagnorisis - the Greek word for 'recognition' or 'discovery', the turning point in a drama at which a character (usually the protagonist) recognizes the true state of affairs, having previously been in error or ignorance
Anahme nape - (Lakota) secret escape
Anamnesis - the recollection or remembrance of the past
Anathema - one who is cursed or damned; one who is greatly reviled, loathed, or shunned; a denunciation invoking a wish or threat of evil or injury; an object of extreme dislike
Anergia - abnormal lack of energy
Angelos - messenger
Animadvert - to comment unfavorably or critically
Anneal - to toughen or temper
Anoesis - a state of mind consisting of pure sensation or emotion without cognitive content
Anomaly - deviation or departure from the normal or common order, form, or rule; one that is peculiar, irregular, abnormal, or difficult to classify
Anomie - a sense of loneliness and anxiety; a lack of social norms, normlessness
Anthropocentric - regarding the human being as the central fact of the universe
Antipathy - a strong feeling of repugnance or enmity; an object of aversion
Aoristic - indefinite, indeterminate
Aphorism - a short pithy instructive saying; a tersely phrased statement of a truth or opinion; an adage
Aphotic - lightless; dark
Aplomb - confidence; coolness
Apodictic - necessarily true or logically certain
Apophenia - the experience of seeing meaningful patterns or connections in random or meaningless data; the perception of or belief in connectedness among unrelated phenomena; believing to see a difference or meaning when the given result is attributable to chance
Aporia - difficulty determining the truth of an idea due to equally valid arguments for and against it; an irresolvable internal contradiction; the expression of doubt or perplexity
Appetence - intense desire; strong natural craving; appetite
Apposite - of striking appropriateness and relevance to a situation or subject; apt; pertinent
Apricity - The sun's warmth on a cold winter day
A priori - not based on prior study or examination; conceived beforehand
Aqueous - watery; consisting of water, like water, or containing water
Arch - cunning, crafty, sly
Arrearage - the state of being behind in the fulfillment of obligations or of being overdue in payment; a payment owed
Asinine - devoid of intelligence; utterly foolish, silly, or foolish; of, relating to, or resembling an ass
Askance - with suspicion, mistrust, or disapproval
Assay - to examine or analyze
Assiduous - diligent; unceasing; persistent; marked by careful unremitting attention or persistent effort
Ataraxia - a state of freedom from emotional disturbance and anxiety
Athazagoraphobia - The fear of forgetting, being forgotten or ignored, or being replaced
Aureate - characterized by an ornate style of writing or speaking
Autocrat - a ruler who has absolute power; someone who insists on complete obedience from others; an imperious or domineering person; a tyrant
Autodidact - one who is self-taught
Autoschediastical - something that is improvised or extemporized
Aver - to assert as true
Axiom - a self-evident or universally recognized truth; maxim; a saying that is widely accepted on its own merits