In the nLab article on Hochschild cohomology it says
Thus, for $A$ a commutative $\infty$-algebra, its Hochschild homology complex is its $(\infty,1)$-tensoring $S^1\cdot A$ with the $\infty$-groupoid incarnation of the circle.
I couldn't find anything online on the notion of a commutative $\infty$-algebra. What is such an object? References are welcome.