What does adenoid mean?
The adenoids are a patch of lymphoid tissue — formally called the pharyngeal tonsil — situated high in the throat, behind the nasal cavity and above the soft palate. Along with the tonsils, they form part of the body's first line of immune defense, helping to trap bacteria and viruses that enter through the nose and mouth. The word is nearly always used in the plural, 'the adenoids', and enters everyday conversation chiefly through children's health: enlarged adenoids are a common cause of snoring, mouth breathing, ear infections, and sleep-disordered breathing in young children. Surgical removal, known as an adenoidectomy, remains one of the most frequently performed pediatric procedures. Interestingly, the tissue naturally shrinks after early childhood and is often barely present by adolescence. The word derives from the Greek 'adēn', meaning gland, combined with '-oid', meaning resembling — literally 'gland-like'.
nounAn adenoid is a mass of lymphoid tissue located at the back of the nasal cavity (the pharyngeal tonsil); the word is most often used in the plural, 'adenoids', to refer collectively to this tissue, especially when enlarged in children.
- (usually plural) A mass of lymphoid tissue (the pharyngeal tonsil) at the back of the nasal passage above the soft palate, part of the immune system.
- (in singular or attributive use) Relating to or characteristic of such tissue, as in 'adenoid tissue' or 'adenoid facies'.
"The doctor recommended removing the child's enlarged adenoids to relieve her chronic congestion."
"Enlarged adenoids can block a child's nasal airway and cause mouth breathing and snoring."
"An adenoidectomy is often performed at the same time as a tonsillectomy."
The plural is the standard, dominant form in both everyday and clinical contexts, since the tissue is discussed as a single collective structure.
"The surgeon removed his adenoids during the same operation as his tonsillectomy."
Your adenoids do their best work in childhood — then they quietly shrink away, often vanishing into near-irrelevance by adulthood.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of adenoid
The word 'adenoid' comes from the Greek 'adēn' (ἀδήν), meaning 'gland', combined with the suffix '-oid', meaning 'resembling' or 'having the form of' — so it literally means 'gland-like'. It entered English medical vocabulary in the nineteenth century, when anatomists applied it to the glandular-looking lymphoid tissue of the nasopharynx. The same Greek root gives rise to related medical terms such as 'adenoma' (a glandular tumor), 'adenovirus', and 'adenine'.
Related word forms
How adenoid is actually used
Almost always used in the plural ('the adenoids') when referring to the anatomical structure; the singular 'adenoid' typically appears in medical or technical contexts. The word carries a clinical register but is familiar to general audiences through childhood health discussions.
Easily confused with adenoid
The thyroid is an endocrine gland in the neck that regulates metabolism, whereas the adenoids are lymphoid tissue behind the nose involved in immune defense.
Tonsils are visible lymphoid masses on either side of the throat, while the adenoids are a similar patch of tissue higher up, behind the nasal cavity.