Starting with "A":
* Aeronautics: The science or practice of designing, building, and operating aircraft.
* Anachronism: Something that is out of place in time.
* Anthropology: The study of humankind, especially its origins, development, and cultures.
* Aquamarine: A pale blue to greenish-blue gemstone.
* Architecture: The art or practice of designing and constructing buildings.
* Avian: Relating to or resembling birds.
Containing "A" within the word:
* Catastrophe: A sudden event that causes great and widespread damage or suffering.
* Dramatically: In a way that is exciting or impressive.
* Emphatically: In a forceful and definite way.
* Fantastically: In a way that is extremely good or impressive.
* Magnificently: In a grand and impressive way.
* Statistically: Relating to the collection, analysis, interpretation, and presentation of data.
Ending with "A":
* Fantasia: A musical composition or artistic work characterized by free and imaginative treatment of its subject matter.
* Panorama: A wide view of a surrounding area.
* Persona: The aspect of someone's character that is presented to or perceived by others.
* Trauma: A deeply distressing or disturbing experience.
Other:
* Alabama: A state in the southeastern United States.
* Galapagos: An archipelago of volcanic islands in the Pacific Ocean.
* Panama: A country in Central America.
These are just a few examples, and there are many other long words with an "A" sound. Do you have any specific criteria in mind? For example, are you looking for words with a specific meaning, or words that are particularly challenging to pronounce?