18-letter words that end in a
- redevelopment area — an urban area in which all or most of the buildings are demolished and rebuilt
- reggio di calabria — a seaport in S Italy, on the Strait of Messina: almost totally destroyed by an earthquake 1908.
- reggio nell'emilia — a city in N Italy.
- relational algebra — (database, theory) A family of algebra with a well-founded semantics used for modelling the data stored in relational databases, and defining queries on it. The main operations of the relational algebra are the set operations (such as union, intersection, and cartesian product), selection (keeping only some lines of a table) and the projection (keeping only some columns). The relational data model describes how the data is structured.
- resaca de la palma — a locality in S Texas, near Brownsville: battle 1846.
- retrograde amnesia — a memory disorder characterized by an inability to remember events or experiences that occurred before a significant point in time.
- sickle cell anemia — a chronic hereditary blood disease, occurring primarily among Africans or persons of African descent, in which abnormal hemoglobin causes red blood cells to become sickle-shaped and nonfunctional, characterized by enlarged spleen, chronic anemia, lethargy, weakness, joint pain, and blood clot formation.
- sickle-cell anemia — Sickle-cell anemia is an inherited illness in which the red blood cells become curved, causing a number of health problems.
- smart battery data — (hardware, protocol) (SBD) A method to monitor a rechargeable battery pack, initiated by Duracell and Intel. An special IC in the battery pack monitors the battery and reports information to the SMBus. This information might include: type, model number, manufacturer, characteristics, discharge rate, predicted remaining capacity, almost-discharged alarm so that the PC can shut down gracefully; temperature and voltage to provide safe fast-charging.
- spinal anaesthesia — anaesthesia of the lower half of the body produced by injecting an anaesthetic beneath the arachnoid membrane surrounding the spinal cord
- spirits of ammonia — a 10% solution of ammonia in alcohol
- stirling's formula — a relation that approximates the value of n factorial (n!), expressed as .
- straits of florida — a sea passage between the Florida Keys and Cuba, linking the Atlantic with the Gulf of Mexico
- structural formula — a chemical formula showing the linkage of the atoms in a molecule diagrammatically, as H–O–H.
- sturt's desert pea — the desert pea
- sub-saharan africa — the region of Africa to the south of the Sahara desert
- superior vena cava — See under vena cava.
- symphony orchestra — a large orchestra composed of wind, string, and percussion instruments and organized to perform symphonic compositions.
- tardive dyskinesia — a disorder characterized by restlessness and involuntary rolling of the tongue or twitching of the face, trunk, or limbs, usually occurring as a complication of long-term therapy with antipsychotic drugs.
- territory of papua — a former territory of Australia, consisting of SE New Guinea and adjacent islands: now part of Papua New Guinea
- the french riviera — the Mediterranean coastal region of France from Cannes eastward to Italy
- the hand of fatima — a symbol of a hand used in some Arabic countries to protect against the evil eye, a magical power
- the intelligentsia — the educated or intellectual people in a society or community
- the queen of sheba — a queen of the Sabeans, who visited Solomon (I Kings 10:1–13)
- valle de la pascua — a city in N Venezuela.
- venezia tridentina — a former department in N Italy, now forming the greater part of the region of Trentino-Alto Adige.
- wernicke's aphasia — a type of aphasia caused by a lesion in Wernicke's area of the brain and characterized by grammatical but more or less meaningless speech and an apparent inability to comprehend speech.
- white-spotted hyla — a type of tree frog (H. leucophyllata) of tropical America