Causal inference is the act of determining the relationship between two variables in which one variable is influenced by the other. There are different synonyms for the term 'causal inference' which includes counterfactual inference, causal reasoning, causation analysis, and causal impact analysis. Counterfactual inference is the process of attributing causality by comparing what would happen under different scenarios. Causal reasoning is the process of establishing certain causes and effects. Causation analysis, on the other hand, is the statistical examination of the relationship between variables to establish cause and effect. Lastly, causal impact analysis is a method for analyzing how a particular factor contributes to a certain outcome. All of these terms refer to the process of determining causality between two variables.