10-letter words containing r, o, a, s
- apocarpous — (of the ovaries of flowering plants such as the buttercup) consisting of separate carpels
- apologiser — Agent noun of apologise; one who apologises.
- aposporous — characterized by apospory
- apostrophe — An apostrophe is the mark ' when it is written to indicate that one or more letters have been left out of a word, as in 'isn't' and 'we'll'. It is also added to nouns to form possessives, as in 'Mike's car'.
- apostrophy — Alternative form of apostrophe.
- apotropous — (of a plant ovule) anatrophous with a ventral raphe
- appointers — Plural form of appointer.
- appointors — Plural form of appointor.
- apportions — Third-person singular simple present indicative form of apportion.
- approaches — Plural form of approach.
- apropos of — with regard to; in respect of
- aquafortis — concentrated nitric acid, used for etching
- aquaporins — Plural form of aquaporin.
- aquiferous — conveying, containing or yielding water
- arachnoids — Plural form of arachnoid.
- araeostyle — having an intercolumniation of four diameters.
- arboresque — a tree.
- arboretums — Plural form of arboretum.
- arc cosine — Trigonometry. the angle, measured in radians, that has a cosine equal to a given number. Symbol: cos −1. Abbreviation: arc cos;
- arc second — Astronomy. second2 (def 4).
- archbishop — In the Roman Catholic, Orthodox, and Anglican Churches, an archbishop is a bishop of the highest rank, who is in charge of all the bishops and priests in a particular country or region.
- archemorus — Opheltes.
- archespore — the cell or group of cells in a sporangium that gives rise to spores
- archivolts — Plural form of archivolt.
- archoplasm — the protoplasmic material surrounding the centrosome, formerly thought to be involved in the formation of the asters and spindle during mitosis
- archosaurs — Plural form of archosaur.
- arcosolium — (in Roman catacombs) an arched recess for a sarcophagus.
- areligious — unconcerned with or indifferent to religious matters.
- arenaceous — (of sedimentary rocks and deposits) composed of sand or sandstone
- argenteous — silvery.
- ariovistus — flourished c71–58 b.c, Germanic leader of the Suevi.
- aristocrat — An aristocrat is someone whose family has a high social rank, especially someone who has a title.
- aristology — the art of eating
- aristotype — a process of photographic printing in which paper coated with silver chloride in gelatin is used.
- armadillos — Plural form of armadillo.
- armigerous — of, having, or entitled to have a coat of arms
- armourless — having no armour
- army corps — a military formation that comprises two or more divisions and additional support arms
- arrowgrass — either of two species, sea arrowgrass (Triglochin maritima) or marsh arrowgrass (T. palustris), of monocotyledonous perennials having long thin fleshy leaves and spikes of inconspicuous flowers
- arrowheads — Plural form of arrowhead.
- arrowsmith — a novel (1925) by Sinclair Lewis.
- arse about — to play the fool; act stupidly, esp in an irritating manner
- arsenolite — a mineral, arsenic trioxide, As 2 O 3 , occurring usually as a white incrustation on arsenical ores.
- art school — tertiary level college for students of art
- arterioles — Plural form of arteriole.
- arthropods — any invertebrate of the phylum Arthropoda, having a segmented body, jointed limbs, and usually a chitinous shell that undergoes moltings, including the insects, spiders and other arachnids, crustaceans, and myriapods.
- artichokes — Plural form of artichoke.
- artocarpus — a genus of the mulberry family, originating in Asia, species of which include the jackfruit and the breadfruit
- arytenoids — Plural form of arytenoid.
- asbjornsen — Peter Christen [pey-tuh r kris-tuh n] /ˈpeɪ tər ˈkrɪs tən/ (Show IPA), 1812–85, Norwegian naturalist and folklorist.