Analgesics.  
Compounds which reduce pain perception, e.g. morphine

Analysis.  
The determination of the components in a chemical sample. Qualitative analysis involves determining the nature of a pure unknown compound or the compound present in a mixture. Various chemical tests exist for different elements or types of compound, and systematic analytical procedures can be used for mixtures. Quantitative analysis involves measuring the proportions of known components in a mixture. Chemical techniques for this fall into two main classes; volumetric analysis and gravimetric analysis. In addition, there are numerous physical methods of qualitative and quantitative analysis, including spectroscopic techniques, mass spectrometry, polarography, chromatography, activation analysis etc.

Anemometer.
An instrument for measurement of gas velocity

Anethole.
1-methoxy-4-prop-1-enylbenzene, C₁₀H₁₂O. while leaflets, with a strong smell and sweet taste, m.p. 22⁰C, b.p. 235⁰C. The chief constituent of anise and fennel oils and other essential oils, from which it is manufactured. It can also be prepared form anisole (methoxybenzene). It is used in medicine, flavouring and in perfuming

Angelic acid, cis 2-methyl-2-butenoic acid,
C₅H₃O₂Mp 45-46 C. b.p. 185C. It occurs free in the roots of Angelic archangel lice.
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When heated alone or with acids or alkalis it is converted to liglic acid (Z) is over Angstorm unit Å a unit of length equivalent to 10^-8 cm. 10^-10m) Used to describe molecular and lattice dimensions and vave-lengths of visible light