Eat
meen,mean,meet,meat,meal
meet, meat, melt, mere, meal, mean,meow......
A six letter synonym for 'alfresco meal' is picnic.
If you mean letter, as in letters of the alphabet, the word is littera. If you mean letter, as in a letter transported by the postal service, the word is epistola.
It can mean 'rice', and it can mean 'meal'.
The word is picnic.
entre
Feast, spread
If you mean the letter "u", I would say Utah is a good bet. But if you mean the word "you" then your is the only one I can think of.
plainly
rid
The word would be "diner."