In English, a specific cat would be referred by the following: the cat. In Bulgarian, a definite article is attached to the end of a noun:

Котка - a cat

Котката - the cat

The article will vary depending on the gender and ending of word:

EndingArticleExamples
Masculine nouns-ът/-а*мъж ➜ мъжът / мъжа*
Feminine nouns-такотка ➜ котката, нощ ➜ нощта
Neuter nouns-токафе ➜ кафето
Plural nouns ending in -а or -я-такафета ➜ кафетата
All other plural nouns-теградове ➜ градовете

References