Catalyzes the hydrolysis of bioactive endogenous fatty acid amides to their corresponding acids (PubMed:12824167). The hydrolysis of endogenous amidated lipids terminates their participation as lipid mediators in various signaling systems (Probable). Converts a wide range of N-acylethanolamines (NAEs) to their corresponding free fatty acids and ethanolamine (PubMed:12824167, PubMed:16624618, PubMed:16738862, PubMed:16880402). Can use oleamide as substrate, but not indole-3-acetamide, 1-naphtalene-acetamide, nicotinic acid amide or L-asparagine (PubMed:16738862). Can use 2-arachidonylglycerol as substrate (PubMed:19801664). Participates in the regulation of plant growth (PubMed:16880402). Hydrolyzes N-dodecanoylethanolamine, which is has a growth inhibitory effect on seedling growth (PubMed:28112243). Involved in plant defense signaling (PubMed:18643971). Involved in abscisic acid (ABA) signaling through mechanisms that are independent of the catalytic activity (PubMed:19801664). Involved in the regulation of flowering time (PubMed:22645580). Catalyzes the hydrolysis of N-acyl L-homoserine lactones (AHLs), which are a class of signaling molecules produced by bacteria for quorum sensing (PubMed:24918118). Accumulation of L-homoserine appears to encourage plant growth at low concentrations by stimulating transpiration, but higher concentrations inhibit growth by stimulating ethylene production (PubMed:24918118). H2O + N-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-ethanolamine = (5Z,8Z,11Z,14Z)-eicosatetraenoate + ethanolamine H2O + N-(9Z,12Z-octadecadienoyl)-ethanolamine = (9Z,12Z)-octadecadienoate + ethanolamine H2O + N-hexadecanoylethanolamine = ethanolamine + hexadecanoate H2O + N-tetradecanoylethanolamine = ethanolamine + tetradecanoate H2O + N-dodecanoylethanolamine = dodecanoate + ethanolamine Inhibited by methyl arachidonyl fluorophosphonate (MAFP). Forms homodimers. Expressed in roots, leaves and flowers (PubMed:16738862). Expressed in seedlings, flowers, roots, siliques, seeds and leaves (PubMed:16880402). Up-regulated during seed germination and early postgerminative seedling growth. No visible phenotype under normal growth conditions (PubMed:16880402). Enhanced sensitivity to inhibition of seedling growth induced by exogenous N-acylethanolamine. Plants overexpressing FAAH exhibit accelerated seedling growth (PubMed:16880402). Plants overexpressing FAAH exhibit enhanced susceptibility to the bacterial pathogen Pseudomons syringae pv tomato (PubMed:18643971). Plants overexpressing FAAH exhibit enhanced sensitivity to abscisic acid (ABA) (PubMed:19801664). Plants overexpressing FAAH exhibit early flowering (PubMed:22645580). Belongs to the amidase family.