| actief | činný rod |
| Actief transport | Endocytóza |
| actinium | aktinium |
| Actinoliet | Aktinolit |
| Action-adventure | Akční adventura |
| ActionScript | ActionScript |
| Active Directory | Active Directory |
| Active Server Pages | Active Server Pages |
| activisme | aktivismus |
| activiteit | činnost |
| activum | činný rod |
| actrice | herec |
| ACTS | ACTS |
| actueel | současný |
| Acubens | Acubens |
| acupunctuur | akupunktura |
| acuut | ostrý |
| AD | AD |
| ad hoc | ad hoc |
| Ad interim | Interval |
| Ada | Ada |
| Ada County | Ada County |
| Ada Lovelace | Augusta Ada King |
| Adad | Iškur |
| Adalbert van Lotharingen | Adalbert |
| Adalbert van Praag | Svatý Vojtěch |
| Adam | Adam |
| Adam Clayton | Adam Clayton |
| Adam en Eva | Adam a Eva |
| Adam Johann von Krusenstern | Adam Johann von Kruzenštern |
| Adam Małysz | Adam Małysz |
| Adam Michna z Otradovic | Adam Václav Michna z Otradovic |
| Adam Mickiewicz | Adam Mickiewicz |
| Adam Opel | Adam Opel |
| Adam Smith | Adam Smith |
| Adamantium | Adamantium |
| Adamello | Adamello-Presanella |
| Adamov | Adamov |
| Adams | Adams |
| Adams County | Adams County |
| adamsappel | ohryzek |
| Adana | Adana |
| Adar | Adar |
| Add-on | Plugin |
| Adda | Adda |
| Addax | Adax núbijský |
| adder | zmije |
| Adders | Zmijovití |
| Adderwortel | Rdesno hadí kořen |
| Addis Abeba | Addis Abeba |
| Additieve kleurmenging | Aditivní míchání barev |
| Address Resolution Protocol | Address Resolution Protocol |
| adelaar | orel |
| Adelaarsgebergte | Orlické hory |
| Adelaarsnevel | Orlí mlhovina |
| Adelaide | Adelaide |
| Adelbert von Chamisso | Adalbert von Chamisso |
| Adelheid | Adelaide |
| adellijk | modrá krev |
| Adelsdorf | Adelsdorfové |
| adem | dech |
