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"La pared" is a form of "pared", a noun which is often translated as "wall". "La mesita" is a form of "mesita", a noun which is often translated as "bedside table". Learn more about the difference between "la pared" and "la mesita" below.
la pared(
pah
-
rehd
)A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
2. (anatomy)
a. wall 
Una perforación nasal aumenta el riesgo de necrosis de la pared nasal.A pierced nose increases the risk of nasal wall necrosis.
a. face 
Se prepararon durante dos años para escalar la pared sureste de El Capitán.They prepared for two years to scale the southeastern face of El Capitan.
la mesita(
meh
-
see
-
tah
)A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
1. (furniture)
a. bedside table  (in a bedroom)
Las pastillas para dormir están sobre la mesita.The sleeping pills are on the bedside table.
b. small table 
Paula colocó una lámpara sobre la mesita del salón.Paula put a lamp on the small table in the living room.