penannular

From Latin paene (“almost”) + annular.

penannular (not comparable)

1. Forming an almost complete ring, but with a break or opening.

• pseudo-penannular

• “penannular”, in OneLook Dictionary Search.
• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “penannular”, in The Century Dictionary […], New York, N.Y.: The Century Co., →OCLC.