# base /ˈbeɪs/ (US) · /bˈeɪs/ (UK) Source: https://englishreference.com/word/base Updated: 2026-08-15 ## Senses ### 1. bottom part noun · CEFR A2 the lowest part of something, which supports the rest. For teachers: the lowest or supporting part of a physical structure or object. - The lamp has a heavy metal base so it does not tip over. - The statue was mounted on a marble base to ensure stability and elevate it above the eye level of the museum visitors. ### 2. military/operations center noun · CEFR B1 a place where a military group or an organization lives and works. For teachers: a center of operations or headquarters for a military or large organization. - The soldiers returned to the base after their training exercise. - The multinational corporation established its regional base in Singapore to oversee its expanding operations across Southeast Asia. ### 3. starting point for ideas noun · CEFR B2 the main idea or fact that you use to start developing something else. For teachers: the fundamental principle or underlying concept from which a logical argument or system is developed. - We used the customer feedback as a base for our new design. - The researcher used the initial findings as a base for a more comprehensive study into urban migration patterns. ### 4. chemistry noun · CEFR B2 · Technical a substance that reacts with an acid to form a salt. For teachers: a substance that can accept hydrogen ions or more generally, donate a pair of valence electrons. - In the science experiment, we mixed a base with an acid. - The laboratory technician carefully measured the pH level to determine the strength of the base before proceeding with the titration. ### 5. mathematics noun · CEFR C1 · Technical the number that is used as the starting point for a system of counting. For teachers: the number of distinct digits used in a positional number system, or the number raised to a power. - Computers use base two, which means they only use zeros and ones. - The binary system operates on a base of two, whereas the decimal system commonly used in daily life operates on a base of ten. ### 6. loyal supporters noun · CEFR B2 a group of people who always support a particular political party or brand. For teachers: a core group of loyal supporters or customers who provide consistent backing. - The politician gave a speech to energize his voter base. - The tech company focused its marketing efforts on its existing user base rather than trying to attract entirely new demographics. ### 7. to use as a foundation verb · CEFR A2 to use one thing as the starting point or reason for another. For teachers: to use a particular fact or situation as the foundation for an idea or action; usually passive. - The movie is based on a book I read last year. - The director decided to base the screenplay on a series of historical letters discovered in a private archive. Usage: Usually used in the passive voice followed by 'on'. ### 8. to be located verb · CEFR B1 to have your main office or home in a certain place. For teachers: to establish a headquarters or center of operations in a specific location. - The company is based in London, but they have offices everywhere. - Although the non-profit is based in Geneva, its field workers are active in over fifty countries across the globe. Usage: Often used in the passive voice followed by 'in' or 'at'. ### 9. immoral adjective · CEFR C1 · Literary · Formal not having good values; acting in a way that is not honest or brave. For teachers: lacking higher values or ethics; dishonourable or cowardly in nature. - He was motivated by base desires like greed and jealousy. - The critic argued that the protagonist's actions were driven by base instincts rather than any sense of duty or altruism. ## Examples - The lamp has a heavy base. - The climbers set up a base camp at the foot of the mountain. - The company's expanding customer base provides a stable foundation upon which it can build future marketing strategies and launch new products. --- From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.