Noun
X-bar
(grammar, X-bar theory) A phrase, or, equivalently, a node in a syntax tree, which consists either of: (1) an adjunct and another X-bar phrase, (2) a head, X, and an optional complement, or (3) a conjunction sandwiched between two other X-bars. The X is a "pro-letter" which can be substituted by letters such as N for noun, V for verb, P for preposition, I for inflectional, etc.
Linguists interested in X-bar theory causally link zero articles to nouns lacking a determiner. Source: Internet
Many other theories of syntax do not employ the X-bar schema and are therefore less likely to encounter this confusion. Source: Internet
This practice is because sentence structure is analysed in terms of a universal schema, the X-bar schema, which sees each head as projecting at least three levels of structure: a minimal level, an intermediate level, and a maximal level. Source: Internet