QUICK ANSWER
"A" is a preposition which is often translated as "to", and "diáfano" is an adjective which is often translated as "diaphanous". Learn more about the difference between "a" and "diáfano" below.
a, la a(
ah
)A preposition is a word that indicates the relationship between a noun and another word (e.g., He ran through the door.).
a. no direct translation
This refers to an idiomatic word or phrase for which there is no word-for-word translation.
Podía respirar a duras penas.He was hardly able to breathe.
a. no direct translation
This refers to an idiomatic word or phrase for which there is no word-for-word translation.
¡A fregar los platos!Go do the dishes!
¡A la cama!Off to bed!
a. no direct translation
This refers to an idiomatic word or phrase for which there is no word-for-word translation.
Me encantaría ganar dinero a espuertas.I would love to earn lots of money.
Llovía a cántaros.It was pouring.
A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
An abbreviation is the shortened form of a word or group of words (e.g., "UFO" = "unidentified flying object"; "p." = "page").
a. A
El circuito transporta una corriente de 1 A.The circuit carries a current of 1 A.
La intensidad de la corriente eléctrica se mide en A.The intensity of an electric current is measured in A.
diáfano(
dyah
-
fah
-
noh
)An adjective is a word that describes a noun (e.g., the big dog).
a. diaphanous
Se veía la cara de la novia por la tela diáfana de su velo.You could see the bride's face through the diaphanous fabric of her veil.
b. translucent
Las cortinas de la sala son diáfanas y por eso entra todo el sol.The curtains in the living room are translucent, so that's why the sun comes in.
c. clear
Las diáfanas aguas de Formentera atraen a muchos buceadores.The clear waters of Formentera attract many scuba divers.
d. crystalline
Las diáfanas aguas de la playa hacen que me sienta en un paraíso.The crystalline waters of the beach make me feel as though I were in paradise.
e. limpid
El agua del lago era tan diáfana que se veían todos los peces.The waters of the lake were so limpid that you could see all the fish.
2. (unclouded)
a. clear
Cuando el cielo está diáfano es cuando más frío hace por acá.When the sky is clear is when it's coldest here.
3. (shiny)
a. bright
La luz diáfana de la lámpara es ideal para leer un libro.The bright light of the lamp is perfect for reading a book.
4. (lucid)
a. clear
La explicación del profesor fue tan diáfana que todos los alumnos la entendieron.The teacher's explanation was so clear that all the students understood it.
a. open-plan
El arquitecto diseñó un espacio diáfano donde todos los empleados trabajarían juntos.The architect designed an open-plan space where all employees would work together.
b. open
Esta habitación diáfana puede convertirse en una sala de juegos para los niños.This open room can become a playroom for the children.