【Expressive】 , 【eloquent】 ,  【significant】 ,  【meaningful】 ,  【pregnant】 ,  【sententious】  mean clearly conveying or manifesting a thought, idea, or feeling or a combination of these.

Something is  【expressive】 which vividly or strikingly represents the thoughts, feelings, or ideas which it intends to convey or which inform or animate it; the term is applicable not only to language but to works of art, to performances (as of music or drama), and to looks, features, or inarticulate sounds.

Something is 【eloquent】 (see also VOCAL 2 ) which reveals with great or impressive force one’s thoughts, ideas, or feelings or which gives a definite and clear suggestion of a condition, situation, or character.

【Eloquent】 is also applicable to words, style, and speech when a power to arouse deep feeling or to evoke images or ideas charged with emotion is implied.

Something is  【significant】 which is not empty of ideas, thoughts, or purpose but conveys a meaning to the auditor, observer, or reader. The term sometimes is applied to words that express a clearly ascertainable idea as distinguished from those words (as prepositions and conjunctions) that merely express a relation or a connection or to works of art or literature that similarly express a clearly ascertainable idea (as a moral, a lesson, or a thesis) as distinguished from works that exist purely for their beauty or perfection of form and have no obvious purpose or import.

More often, 【significant】 applies to something (as a look, gesture, or act) that suggests a covert or hidden meaning or intention.

Something is  【meaningful】  which is 【significant】 in the sense just defined; the term is often preferred when nothing more than the presence of meaning or intention is implied and any hint of the importance or momentousness sometimes associated with  【significant】 would be confusing.

Something is  【pregnant】 which conveys its meaning with richness or with weightiness and often with extreme conciseness or power.

Something is  【sententious】 which is full of significance; when applied, as is usual, to expressions, the word basically connotes the force and the pithiness of an aphorism. But even as an aphorism may become hackneyed, so has  【sententious】 come to often connote platitudinousness or triteness.