semicircle noun A half of a circle, bounded by a diameter and half of the circumference. The students arranged their chairs in a semicircle facing the teacher. + semicolon noun A punctuation mark (;) used to join two closely related independent clauses or to separate items in a complex list. She loves reading novels; she visits the public library nearly every weekend to find something new. + semifinal noun One of two matches or rounds played to decide who advances to the final of a competition. Our team lost the semifinal in a close match decided by penalty kicks. + semiannual adjective Occurring or produced twice a year, at intervals of about six months. The company holds a semiannual review to assess each employee's progress and goals. + semiconductor noun A material, such as silicon, whose electrical conductivity falls between that of a conductor and an insulator, used in electronics. Modern computer chips are built from thin layers of semiconductor material like silicon. + semiconscious adjective Partly conscious; only slightly aware of one's surroundings, as when barely awake or recovering from a blow or anesthesia. He was semiconscious after the crash and could only mumble a few words to the paramedics. + semidetached adjective Describing a house that is joined to one neighboring house by a shared wall, with the other side standing free. They bought a semidetached house with a small garden on one side. + semiformal adjective Moderately formal in style, especially of dress or an event, less strict than black-tie but dressier than casual. The invitation called for semiformal attire, so he wore a blazer without a tie. + semiprecious adjective Describing gemstones, such as amethyst or garnet, valued for their beauty but less rare and costly than precious stones like diamonds. She wore a necklace set with semiprecious turquoise stones from a local market. + semiautomatic adjective Describing a machine, especially a firearm, that performs part of a repeated action automatically but needs a manual trigger pull for each cycle. The semiautomatic rifle fires one round each time the trigger is pulled, then reloads itself. + semiliterate adjective Able to read and write only with difficulty or to a very limited degree. Many rural workers of that era were semiliterate, able to sign their names but little more. + semipermanent adjective Lasting for a moderate but limited time rather than permanently; intended to be temporary but durable. She got a semipermanent hair dye that would fade after about six weeks. + semiretired adjective Having largely, but not completely, stopped working, often by reducing hours or taking on occasional projects. After selling his company, he became semiretired and now consults a few days a month. + semisweet adjective Having a moderate amount of sugar, especially describing chocolate that is sweeter than bittersweet but less sweet than milk chocolate. The cookie recipe calls for a cup of semisweet chocolate chips. + semitransparent adjective Allowing some light to pass through while still partly blocking a clear view; translucent. The frosted glass door was semitransparent, showing shapes but no clear details. + semitropical adjective Having a climate that resembles the tropics in warmth and humidity but lies just outside the tropical zone; subtropical. Palm trees and citrus groves thrive in the semitropical climate of southern Florida. + semiarid adjective Describing a climate or region that receives slightly more rainfall than a desert but still too little to support most crops without irrigation. The semiarid plains support scrubby grasses and drought-resistant shrubs rather than dense forest. + semidarkness noun A state of partial darkness in which some light is present but visibility is still limited. We ate dinner in semidarkness after the power flickered but didn't fully go out. + semiskilled adjective Having or requiring some training but not the extensive expertise of a fully skilled trade. The factory hired semiskilled workers and trained them on the specific assembly line. + semisolid adjective Having a consistency between solid and liquid; thick and firm but not fully rigid. The pudding cooled into a semisolid mass that clung to the spoon. + semiprofessional adjective Engaging in an activity, especially a sport or art, for pay but not as a full-time primary occupation. He plays semiprofessional soccer on weekends while working a full-time job during the week. + semicentennial noun A fiftieth anniversary of an event, or the celebration held to mark it. The town held a parade to mark the semicentennial of its founding. +