"Association by similarity" refers to the act of linking or comparing different things which possess similar characteristics or qualities. Some common synonyms for this phrase include resemblance, likeness, affinity, analogy, correspondence, parallel, comparison, and connection. These words can be used interchangeably depending on the context or emphasis of the particular situation. For example, when describing a particular artwork, one could say that it bears a strong resemblance to another famous piece, or that it shares a likeness with a particular artistic style. These synonyms help to enrich our vocabulary, allowing us to express our thoughts and ideas more precisely and effectively.