Pithy means short, pointed and full of meaning. A pithy remark, pithy and quotable, keep it pithy.
The praise is in the density: a pithy line says a great deal in very few words, which is why it is what editors ask for. The pith is the soft core of a stem, and the sense of the essential thing came from there.
1adjectivepithyShort, pointed and full of meaning.
“The teacher wrote a pithy comment at the end of my long essay: "Less is more."”
pithy is a quality.
From pith, the soft core of a plant stem, plus -y, by way of the sense of the essential part.
Middle English
pithy,pythy
English, today
pithy
From Middle English pithy,pythy, equivalent to pith + -y.
Etymology from Wiktionary, CC BY-SA