Consider the phrase:
Here "好き" is a na-adjective, and this sentence could translate to:
Question: Is the 形容動詞 in this phrase:
- ...just the word "好き"?
- ...the logical clase "好きな"?
- ...or the whole thing: "好きな人"?
When you talk about the word, it's 好き. （だろ だっ・で・に だ な なら NA） are the conjugation list of 形容動詞 in modern Japanese (口語). 好きだ is called 基本形, 好き being 語幹 (stem). 好きな is just a 形 of this word--連体形, the form it takes when it is used as a 連体修飾語. I'm guessing it looks more familiar to you because in Japanese pedagogy and learner's grammar it is called "na-adjective" which is admittedly confusing.
The answer to this question is actually arguably "it depends on who you're talking to".
For English, most grammarians share a pretty consistent view of how the language grammar is described and taught, and everybody learns it the same way. However, with Japanese there are actually a number of different schools of thought regarding how the grammar of the language can be divided up and described, and they look at some aspects of it slightly differently from each other. (It's important to understand that with languages, grammar rules are essentially something made up by humans to try to describe observed usage, so there can be multiple ways to describe the same thing which are equally valid, and really just a matter of perspective.)
In some schools of thought (which are more commonly taught in Japan), the な (or だ, etc, when used in sentence-final position) associated with a な-adjective (形容動詞) is considered to be part of the word, and so these words are effectively conjugated with different endings for different situations, similar to verbs or い-adjectives. (This is why the Japanese term actually has 動詞 in it, because when viewed in this way, they are sorta considered to work similarly to verbs grammatically.)
In other schools of thought (often more common outside of Japan), な-adjectives themselves do not include the な as part of the word, and do not conjugate (more similar to how nouns work), and the な is just considered to be a separate particle (or seen as a form of the copula だ, depending on who you talk to) which is attached to them when forming the sentence.
Both are arguably equally valid ways of looking at things, it just depends which system of describing Japanese grammar you are working with.
It is important to note that there is another category of adjectives which are often confused for 形容動詞 but actually are not, and behave slightly differently. These are 連体詞 (often called "rentaishi adjectives" or "adnominal adjectives" in English). Many of these adjectives also end in な, but the ending な is always considered to be part of the word in both schools of thought.
NA adjectives are nouns that have Chinese origin in general and started being used as adjectives. In classical Japanese there were two kinds òf adjectives. Some used to take the copula たり and some なり. The 連体形 of なり is なる. Therefore 静かなる部屋 became 静かな部屋. The old 連体形 of たり, たる is still used nowadays in modern Japanese. Example: 堂々たる態度. 好きだ is the predicative form that comes in the end 終止形. 好きな is the 連体形 because it has the 連体形 of the old copula なり. 好き is the 辞書形/語幹.