llastra/l.lastra - stone slab - piedra plana

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Llastra: pronounced YAH-strah. In West Asturias the variant l.lastra is pronounced TSAH-strah. Noun designating a stone or boulder, usually with a flat surface. The stone slab can be found either on the ground or out at sea. Asturians may refer to a llastrona if the stone is especially large.

According to the etymological dictionary of Joan Corominas, the origin of the word predates the Roman invasion of the Iberian Peninsula. Place names like the fishing port of Llastres (Lastres, in Spanish; literally, ‘many flat stones’) attest to its ancient roots. Others contend it may be related to a modern Italian term for pavement: lastrica.

Usage examples:

Taivos con cuidau que hai una llastra nesi prau que fai esbariar. [Be careful with the flat stone in that field because you may slip and fall.]
Nalando la travesia Candas-Xixon el branu pasau toparame con una llastrona en meta la mar. [During the open sea swim last summer from Candas to Xixon, I stumbled upon a large flat stone in middle of the ocean.]
Nolo tuvo a piques d’espetase col coche escontra la llastra. [Nolo was pretty close to smashing his car against the boulder.]
A llastra da Filadoira podese ver dende o Pico Gargalois. [The dolmen known as ‘A llastra da Filadoira’ can be seen from Mt. Gargalois.]

Here is a picture of A Llastra da Filadoira, a dolmen in County Eilao (Illano), in West Asturias. Megalithic tombs like this were often known as ‘llastras’ or ‘pedruas’ by locals because of the large stones. In this case, the capstone is made of slate.