weighty (tome, issues)	ważki (abstract and physical things, idea of seriousness)
unwieldy (discussions, object)	nieporęczny (abstract and physical things, idea of difficult to handle)
cumbersome (procedure, weapon)	nieporęczny, uciążliwy (for equipment, machines difficult to handle, for systems)
burdensome (duty)	obarczający (usually used of abstract things)
ponderous (tone of voice, thesis)	przyciężkawy, niezgrabny (used of abstract things, serious but with negative connotation)
lumbering (truck, reptiles)	ociężały (for physical things, often suggesting heavy movement)
to be weighed down with sth	carrying very heav things
to weigh up	to consider and compare (rozważać)
to weigh out	to weigh a quantity of loose goods (odważać)
to weigh on sb	troubling sb's mind (ciążyć komuś)
to weigh in	to add more points to the argument
to thicken	to make thicker (zagęścić)
to sift	to shake it in a sieve to separate the grains (przesiewać)
lumpy	have solid pieces in it (nierówny)
to congeal	to become thick and solid (zakrzepnąć)
to solidify	to become solid (stężeć)
to thin	to make thinner (rozrzedzić)
to dilute sth/ to water sth down	to add water (rozwodnić)
to thin out	to become less dense
to thin one's hair out	to make one's hair less thick
impenetrable	impossible to move through (nieprzenikniony)
impermeable	no liquid or gas can pass through
impervious	liquid cannot pass through (nieprzepuszczalny)