Sister Block

(Naut.) a tackle block having two sheaves, one above the other.

See also: Sister

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
The showroom and branch join Mutual Materials' 17 other such facilities, plus Lacey and sister block and brick operations in Washington, Oregon, Idaho Montana and British Columbia.
"There is a sister block that is exactly the same design to Lakanal House and the residents there haven't been able to sleep since Friday night because, until we know the cause, they can't be sure the same thing won't happen there."
JAMMED: Fire-door CHILLING: Warning sign at flats ALARM: Only exit at Lakanal's sister block
Mr Tarling examined Marie Curie house, the sister block to Lakanal House, a few days after the fire.
In this book you will find 25 interchangeable sister blocks and three sampler quilts that challenge traditional grid layouts with fun, innovative settings.
I remember my sister blocked my bedroom door once to stop him from getting in to kill me (that's what he was saying he wanted to do).
Jodie told coroner Roger Whittaker that her sister blocked the doorway to the balcony with a baby walker so she couldn't get to her.