Definition: The word 'achene' translates to 'dust' in English, but it should be noted that this term may refer to a variety of things depending on context. In nature, dust is usually a small, fine particle of material suspended in an air column or cloud. In a chemical process where the molecules of gas or liquid are condensed into solid form as they pass through a vacuum, this phenomenon can occur called condensation. Condensation can also refer to the motion or movement of particles within a substance. In more general terms, dust may also be considered as small bits of material that are removed from an area by means of a process known as air filtration. This term is commonly used in engineering and laboratory contexts where the goal is to remove substances from a region by filtration methods such as vacuum filtration or centrifugation. So while the word 'achene' may not be easily defined, it can often be taken to mean anything that contains dust-like particles and moves or falls in an air column.