A Lewis acid is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct.
 A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis acid to form a Lewis adduct.
 For example, NH is a Lewis base, because it can donate its lone pair of electrons.
 MeB is a Lewis acid as it is capable of accepting a lone pair.
 In a Lewis adduct, the Lewis acid and base share an electron pair furnished by the Lewis base, forming a dative bond.
 In the context of a specific chemical reaction between NH and MeB, the lone pair from NH will form a dative bond with the empty orbital of MeB to form an adduct NH•BMe.
 The terminology refers to the contributions of Gilbert N. Lewis.
In chemistry, a single bond is a chemical bond between two atoms involving two valence electrons.
 That is, the atoms share one pair of electrons where the bond forms.
 Therefore, a single bond is a type of covalent bond.
 When shared, each of the two electrons involved is no longer in the sole possession of the orbital in which it originated.
 Rather, both of the two electrons spend time in either of the orbitals which overlap in the bonding process.
 As a Lewis structure, a single bond is denoted as AːA or A-A, for which A represents an element (Moore, Stanitski, and Jurs 329).
 In the first rendition, each dot represents a shared electron, and in the second rendition, the bar represents both of the electrons shared in the single bond.
A coordinate covalent bond, also known as a dative bond or coordinate bond is a kind of 2-center, 2-electron covalent bond in which the two electrons derive from the same atom.
 The bonding of metal ions to ligands involves this kind of interaction.
The charge-shift bond has been proposed as a new class of chemical bond that sits alongside the two familiar families of covalent and ionic bonds where electrons are shared or transferred respectively.
 The charge shift bond derives its stability from the resonance of ionic forms rather than the covalent sharing of electrons which are often depicted as having electron density between the bonded atoms.
 A feature of the charge shift bond is that the predicted electron density between the bonded atoms is low.
 It has long been known from experiment that the accumulation of electronic charge between the bonded atoms is not necessarily a feature of covalent bonds.
 An example where charge shift bonding has been used to explain the low electron density found experimentally is in the central bond between the inverted tetrahedral carbons in [1.1.1]propellanes. Theoretical calculations on a range of molecules have indicated that a charge shift bond is present, a striking example being fluorine, F, which is normally described as having a typical covalent bond.
The covalent bond classification (CBC) method is also referred to as the LXZ notation.
 It was published by M. L. H. Green in the mid-1990s as a solution for the need to describe covalent compounds such as organometallic complexes in a way that is not prone to limitations resulting from the definition of oxidation state.
 Instead of simply assigning a charge to an atom in the molecule (i.e. the oxidation state), the covalent bond classification method analyzes the nature of the ligands surrounding the atom of interest, which is often a transition metal.
 According to this method, there are three basic types of interactions that allow for coordination of the ligand.
 The three types of interaction are classified according to whether the ligating group donates two, one, or zero electrons.
 These three classes of ligands are respectively given the symbols L, X and Z.
A symmetric hydrogen bond is a special type of hydrogen bond in which the proton is spaced exactly halfway between two identical atoms.
 The strength of the bond to each of those atoms is equal.
 It is an example of a 3-center 4-electron bond.
 This type of bond is much stronger than "normal" hydrogen bonds, in fact, its strength is comparable to a covalent bond.
 It is seen in ice at high pressure (Ice X), and also in the solid phase of many anhydrous acids such as hydrofluoric acid and formic acid at high pressure.
 It is also seen in the bifluoride ion [F−H−F].
 Much has been done to explain the symmetric hydrogen bond quantum-mechanically, as it seems to violate the duet rule for the first shell: The proton is effectively surrounded by four electrons. Because of this problem, some consider it to be an ionic bond.
Gilbert Newton Lewis {'1': ", '2': ", '3': 'ForMemRS', '4': "} (October 25 (or 23), 1875 – March 23, 1946) was an American physical chemist known for the discovery of the covalent bond and his concept of electron pairs; his Lewis dot structures and other contributions to valence bond theory have shaped modern theories of chemical bonding.
 Lewis successfully contributed to thermodynamics, photochemistry, and isotope separation, and is also known for his concept of acids and bases.
A four-center two-electron bond (4c–2e bond) is a type of chemical bond in which four atoms share two electrons in bonding, with a net bond order of ⁄ .
 This type of bonding differs from the usual covalent bond, which involves two atoms sharing two electrons (2c–2e bonding).
A carbon–carbon bond is a covalent bond between two carbon atoms.
 The most common form is the single bond: a bond composed of two electrons, one from each of the two atoms.
 The carbon–carbon single bond is a sigma bond and is formed between one hybridized orbital from each of the carbon atoms.
 In ethane, the orbitals are sp-hybridized orbitals, but single bonds formed between carbon atoms with other hybridisations do occur (e.g. sp to sp).
 In fact, the carbon atoms in the single bond need not be of the same hybridisation.
 Carbon atoms can also form double bonds in compounds called alkenes or triple bonds in compounds called alkynes.
 A double bond is formed with an sp-hybridized orbital and a p-orbital that isn't involved in the hybridization.
 A triple bond is formed with an sp-hybridized orbital and two p-orbitals from each atom.
 The use of the p-orbitals forms a pi bond.
Isopeptag is a 16 amino acid peptide tag (TDKDMTITFTNKKDAE) that can be genetically linked to proteins without interfering with protein folding.
 What makes the isopeptag different from other peptide tags is that it can bind its binding protein through a permanent and irreversible covalent bond.
 Other peptide tags generally bind their targets through weak non-covalent interactions, thus limiting their use in applications where molecules experience extreme forces.
 The isopeptags covalent binding to its target overcomes these barriers and allows target proteins to be studied in harsher molecular environments.

Question: What type of acid was named for the discoverer of the covalent bond?
Answer: Lewis acid