Glossary L

Deutsch: Lethargie / Español: Letargo / Português: Letargia / Français: Léthargie / Italiano: Letargia

Lethargy in psychology refers to a state of profound fatigue, sluggishness, or lack of motivation that extends beyond ordinary tiredness. It is characterized by a persistent reduction in energy, cognitive function, and emotional responsiveness, often impairing daily functioning. While lethargy can manifest as a symptom of various psychological or medical conditions, its underlying mechanisms and clinical significance require careful differentiation from similar states such as apathy or depression.

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Letter level is defined as the level of written perception in which a visual stimulus is represented as a letter of the alphabet.

Letter of recommendation refers to a letter expressing an opinion regarding an applicant’s ability, previous performance, work habits, character, or potential for success.

Letter-sound correspondences is the principle that each letter represents a unit of sound (a phoneme).

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Leucocytes refers to white blood cells that find and destroy antigens

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Leukemia is a cancer originating in blood or blood-producing cells. Leukemias are cancers that are found in the blood and bone marrow.

Leukocyte is white blood cell; a component of the immune system Leukocytes, moreover, are white blood cells (WBCs). The key cells to the immune system.

Lev Semionovich Vygotsky (1896-1934) Vygotsky was born in Russia in the same year as Piaget. Vygotsky was not trained in science but received a law degree from the Moscow University.

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