Complex sentence: Semantic similarity measures the likeness of terms, words, documents or any objects which can be characterized through semantics which is based on their meaning or semantic content, as opposed to similarity which can be estimated regarding their syntactical representation (e.g. their string format).
Split into simpler sentences: Semantic similarity measures the likeness of terms, words, documents or any objects which can be characterized through semantics. The likeness of objects is based on their meaning or semantic content, as opposed to similarity which can be estimated regarding their syntactical representation (e.g. their string format).