**Core Concept**
Glossodynia refers to pathological pain in the tongue, specifically a persistent, often dull or sharp, sensation without visible signs of injury or inflammation. It is a symptom of underlying conditions such as oral infections, trauma, or systemic diseases, and is distinct from other tongue abnormalities.

**Why the Correct Answer is Right**
Glossodynia is defined as pain in the tongue, whether sharp, dull, or burning, and is the key clinical feature. The term "glossodynia" literally means "tongue pain" (from *glossa* = tongue, *-dyne* = pain). It does not imply swelling or visible lesions, making pain the central component. This is a symptom, not a sign, and is often associated with neuropathic, inflammatory, or metabolic causes.

**Why Each Wrong Option is Incorrect**
Option B: Burning of the tongue is a symptom that may occur in glossodynia, but it is not the definition of glossodynia. "Burning" is a type of pain, not the full clinical description.
Option C: Swelling of the tongue is a physical sign, not a feature of glossodynia. Swelling is associated with conditions like angioedema or infections, not glossodynia.
Option D: A white patch (e.g., leukoplakia) is a visible lesion, not a symptom of pain. It may be associated with oral precancerous conditions but is not synonymous with glossodynia.

**Clinical Pearl / High-Yield Fact**
Glossodynia is a common presenting symptom in patients with neuropathic pain, vitamin deficiencies (like B12), or oral candidiasis. Always assess for underlying causes—especially in elderly or immunocompromised patients—before attributing it to simple irritation.

✓ Correct Answer: A. Pain in the tongue