The compound adjective "tar-like" is a transparent formation from two ancient Germanic roots. The first element, "tar," descends from the Old English word for the dark, viscous substance derived from organic materials like wood or coal. The second element, "-like," originates from the Old English suffix -līc, which denoted having the body or form of something, a concept rooted in the Proto-Germanic word for body. The logic of the word is straightforward and modern: it directly compares a substance's physical properties—such as its consistency, color, and adhesiveness—to those of tar. This descriptive compound follows a common English pattern for creating similitudinal adjectives, where a noun is combined with "-like" to indicate resemblance.

Structure: tar (substance) + like (resembling) - tar: From Old English teoru, teru, meaning a dark, viscous liquid. Origin: Proto-Germanic. - like: From Old English līc, meaning body, form; from the suffix -līc, meaning having the form of. Origin: Proto-Germanic.