You can evaluate how processed a food is by reading the label's ingredients list to see the names, number, and type of ingredients. A large number of ingredients, with names that you don't recognize, indicates a highly processed food.
More generally, virtually every food that has a label is processed. Virtually every food that comes in a box, bag, jar, or can is processed.
List of processed foods
Baked goods and grains
White rice
Cornmeal
Polenta
Flour
White flour
Bread
Rolls
Buns
Muffins
Bagels
Bread sticks
Pizza crust
Pita bread
Tortillas
Croutons
Flat bread
Crackers
Macaroni
Pasta
Couscous
Orzo
Cake
Cake mixes
Pie
Pie crust mixes
Cookies
Cookie dough
Salt and leavens
Salt
Baking powder
Baking soda
Processed Fruit
Canned fruit
Frozen fruit
Fruit sauces
Jellies
Jams
Pie fillings
Fruit juice
Processed vegetables
Canned vegetables
Frozen vegetables
French fries
Ketchup
Mustard
Convenience foods
Pizza
Precooked foods
Frozen dinners
Breakfast cereal
Granola
Energy bars
Processed meat
Canned meat
Cured meat
Ham
Lunch meat
Sausage
Bacon
Gelatins
Fresh meat with additives
Processed dairy foods
Cheese
Cheese food
Milk other than raw (homogenized, pasteurized, skim, low-fat, etc.)
Yogurt
Processed fats and oils
Refined oils
Cooking spray
Margarine
Salad dressing
BBQ sauce
Mayonnaise
Peanut butter
Drinks
Soft drinks
Fruit drinks
Instant breakfast drinks
Confections
White sugar
Brown sugar
Corn syrup
Rice syrup
Honey (unless raw)
Syrups
Candies
Soft candies
Pudding
Dessert mixes
Ice cream
Frozen desserts
Whipped cream
Chocolate
Marshmallows
Shredded coconut
Sugar Subtitutes