1. Easily startled; timid.
2. 1. Drawing back from contact or familiarity with others; retiring or reserved.
   2. Marked by reserve or diffidence: a shy glance.
3. Distrustful; wary: shy of strangers.
4. Not having paid an amount due, as one's ante in poker.
5. Short; lacking: Eleven is one shy of a dozen.

1. To move suddenly, as if startled; start.
2. To draw back, as from fear or caution; recoil.

Synonyms: These adjectives mean not forward but marked by a retiring nature, reticence, or a reserve of manner. One who is shy draws back from others, either because of a withdrawn nature or out of timidity: "The poor man was shy and hated society" (George Bernard Shaw).
Bashful suggests self-consciousness or awkwardness in the presence of others: "I never laughed, being bashful./Lowering my head, I looked at the wall" (Ezra Pound).
Diffident implies lack of self-confidence: He was too diffident to express his opinion.
Modest is associated with an unassertive nature and absence of vanity or pretension: Despite her fame she remained a modest, unassuming person.
Coy usually implies feigned, often flirtatious shyness: "yielded with coy submission" (John Milton).
Demure often denotes an affected shyness or modesty: Her assistant nodded in agreement, flashing a demure smile.