| Gaelic | Part of Speech | English |
|---|---|---|
| cailsium | n(m) | calcium |
| cailsium carbonat | n(m) | calcium carbonate |
| cairt | n(f) | card |
| cairt didsiotach | digital card | |
| cairt-ceangail | connection card | |
| cairteal | n(m) | quarter |
| cairteal | n(m) | quartile |
| cairtealaich | vb | quarter |
| cairtealaichte, air a chairteal(ach)adh | adj | quartered |
| cairtean didsiotach | digital cards | |
| cairtean-dùbhlain | challenge cards | |
| cairt-fhigearan | digit card | |
| caisead | n(m) | gradient |
| caiseid | poss c | gradient |
| caith | vb | spend |
| caitheadair | n(m) | consumer (food chain) |
| caochladair | n(m) | variable |
| caol | adj | acute |
| carbohaidhdreat | n(m) | carbohydrate |
| carbonat | n(m) | carbonate |
| ceangailte | adj | composite |
| cearcallaiche | compasses | |
| ceàrn caol | acute angle | |
| ceàrnag | n(f) | square |
| ceàrnagach | adj | square |
| ceàrnagaich | vb | square |
| ceàrnaichte | adj | squared |
| ceàrnanach | adj | quadratic |
| ceart | adj | right |
| ceart-cheàrnach | adj | perpendicular |
| ceart-cheàrnach | adj | right-angled |
| ceart-cheàrnach | n(m) | rectangle |
| ceart-cheàrnachail | adj | rectangular |
| ceart-cheàrnachan | pl | rectangles |
| ceart-cheàrnaich | poss c | rectangle |
| ceasnachadh | n(m) | enquiry |
| ceasnachaidh | poss c | enquiry |
| ceasnachaidhean | pl | enquiries |
| ceasnachaidhean | pl | enquiries |
| ceasnachaidhean | pl | enquiries |
| ceasnachaidhean | pl | enquiries |
| ceasnaich | vb | enquire |
| ceithir-cheàrnach | n(m) | quadrilateral |
| ceithir-cheàrnaich | poss c | quadrilateral |
| ceud | n/adj | hundred |
| ceudachd | n(f) | percentile |
| ceudachd | poss c | percentile |
| ceudad | n(m) | percentage |
| ceudadach | adj | percentage |
| ceudadan | pl | percentages |
| ceudaid | poss c | percentage |
| ceudaliotair | n(m) | centilitre |
| ceudaliotair | centilitre | |
| ceudameatair | centimetre | |
| ceudan, deichean & aonadan | hundreds, tens & units | |
| cg | abbr | kg |
| cileagram | n(m) | kilogram |
| cìs | n(f) | tax |
| ciùb | n(m) | cube |
| ciùb | vb | cube |
| ciùbach | adj | cubic |
| ciùbaichte | adj | cubed |
| ciùbaid | n(f) | cuboid |
| ciùbaidean | pl | cuboids |
| ciùb-ceangail | linking cube | |
| clach atharrachail | n(f) | metamorphic rock |
| clach ghrùideach | n(f) | sedimentary rock |
| clach theinnteach | n(f) | igneous rock |
| clàr | n(m) | table |
| clàran-srutha | pl | flowcharts |
| clàr-fhiacail | n(f) | incisor |
| clàr-shràcan | tally chart | |
| clàr-srutha | n(m) | flowchart |
| clì | adj | left |
| cliath | n(f) | grid |
| clòimh-liath | n(f) | mould |
| clòimh-liathach | adj | mouldy |
| clòraid | n(m) | chloride |
| clòrofail | n(m) | chlorophyll |
| clòroplast | n(m) | chloroplast |
| co-amail | adj | simultaneous |
| co-aontar | n(m) | equation |
| co-astarail | adj | equidistant |
| co-chasach | adj | isosceles |
| co-chasach | adj | isoscles |
| co-chomharra | n(m) | coordinate |
| co-chòrdach | adj | congruent |
| co-chòrdachd | n(f) | congruence |
| co-chothromachd | symmetry | |
| co-chur | n(m) | application |
| còd | n(m) | code |
| co-fhreagairt | adj | fitting |
| co-fhreagarrach | adj | corresponding |
| còig-cheàrnach | n(m) | pentagon |
| còig-cheàrnachail | adj | pentagonal |
| còigeamh | n(m) | fifth |
| coimeas | n(m) | comparison |
| co-iomlaideach | adj | commutative |
| co-ionannachd | n(f) | equivalence |
| colbh | n(m) | column |
| co-leasachail | adj | supplementary |
| coltachd | n(f) | probability |
| coltachd cho-ionann | equal probability | |
| comharra-chunntaidh | poss c | tally mark |
| comharra-chùrsa | poss c | direction indicator |
| comharra-cunntaidh | n(m) | tally mark |
| comharra-cùrsa | n(m) | direction indicator |
| comharradh | n(m) | notation |
| comharraidh | poss c | notation |
| comharraidhean | pl | notations |
| comharran-cunntaidh | pl | tally marks |
| comharran-cùrsa | pl | direction indicators |
| co-mheadhanach | adj | concentric |
| co-mheas | n(m) | ratio |
| còn | n(m) | cone |
| còna | poss c | cone |
| conadal | adj | odd one out |
| co-phàirteach | adj | complementary |
| còrd imleig | n(m) | umbilical cord |
| cosgais | cost | |
| cosgais | cost | |
| cosgais | cost | |
| co-shìnteach | adj | parallel (electric) |
| co-thàthadh | n(m) | compound |
| cotyledon | n(m) | cotyledon |
| cridhe eitean na talmhainn | n(m) | inner core (of the earth) |
| cuartachadh | n(f) | convection |
| cuartachadh blàiths | n(m) | heat convection |
| cumadh ceangailte | composite shape |